s St

ec

S

clen

(NASA-CP-3165-Vol-2) NSSOC

CONFERENCE ON MASS STORAGE SYSTEMS

AND TECHNOLOGIES FOR SPACE ANO

EARTH SCIENCE APPLICATIONS, VOLUME

2 (NASA) 257 p

!cation 3165, Vol. H

rence on

ystems

no ogies for

and Earth

lications

Volume H

N93-16320

--THRU--

N93-16333

Unclas

H1/82 0126634

NASA Conference Publication 3165, Vol. H

NSSDC Conference on

Mass Storage Systems

and Technologies for

Space and Earth

Science Applications

Volume H

Edited by

Ben Kobler

Goddard Space Flight Center

Greenbelt, Maryland

P. C. Hariharan

and L. G. Blasso

STX Corporation

Lanham, Maryland

Proceedings of a conference held at

NASA Goddard Space Flight Center

Greenbelt, Maryland

July 23-25, 1991

National Aeronautics and

Space Administration

Office of Management

Scientific and Technical

Information Program

1992
Z

I

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v

i
Preface

The National Space Science Data Center (NSSDC) at NASA's Goddard Space Flight Center has

been charged with the archiving of data collected from NASA's scientific spaceflight missions

flown over the past 30 years. During this time NSSDC has accumulated an archive of several

terabytes of data. In the coming years NASA will be generating this volume of data every few

days or less. Thus, data storage media and systems become critically important to NASA if it is

to successfully manage this data volume and to have a chance to transform these data into

scientific knowledge.

NSSDC wiU play an important role in NASA's awareness of and exploitation of emerging mass

storage systems, both at NSSDC and in the increasingly distributed NASA scientific data

environment. For this reason, NSSDC organized a conference at Goddard in the summer of

1991 to review the status of and the outlook for data storage media and systems. Leading

experts in each of several areas were invited to make presentations, and a highly informative

conference transpired. In order that the record of that conference be preserved, this set of

presentations is being published.

The Proceedings of the NSSDC Conference on Mass Storage Systems and Technologies for

Space and Earth Science applications are published in four volumes, with each of the first

three volumes containing the talks and presentations for that particular day. Discussions

following some of the talks are collected in the fourth volume along with introductory

biographical material on the speakers. Despite our best efforts, the questions and answers were

sometimes inaudible to the transcriptionist. An effort was made to contact the participants to

clarify the transcript, and we are grateful to the speakers who cooperated.

The success of an endeavor of this magnitude depends on the generous help and cooperation of

the participants. We would like to record our gratitude to the speakers, the audience, and in

particular, to the following individuals and organizations for their assistance:

The Program committee whose membership is listed in the front of each volume

The session chairs who kept the schedule on track:

Professor Bharat Bhushan of Ohio State University

Dr. Barbara Reagor of Bellcore

Dr. Robert Freese of Alphatronix

Mr. Patric Savage of Shell

Professor John C. Mallinson of Mallinson Magnetics

Dr. Kenneth Thibodeau of the National Archives and Records Administration

The members of the Panel Discussion and Professor Mark Kryder of Carnegie

Mellon University who moderated the discussion

The hard-working crew from Westover Consulting

Dr. Dennis E. Speliotis of Advanced Development Corporation for his help with

the transcript of the Panel Discussion

Dr. James L. Green and the National Space Science Data Center

PRECE_i_G _'_,C,E _::_L;_i-._.__0"( FILMED

Dr. J. H. King

Dr. P. C. Hariharan

Benjamin Kobler

o..

111
NssDC_Mass Storage Conference Committee

Ben K0bler, NASA/GSFC (Chair)

John Berbert, NASA/GSFC

Sue Kelly, DOE/Sandia

Elizabeth Williams, SRC/Bowie

Ai Dwyer, STX Corporation *

P. C. Hariharan, STX Corporation *

Sanjay Ranade, STX Corporation *

z

Conference Coordinator i

Kim Blackwell, STX Corporation *

* Hughes STX Corporation as of October 1, 1991

iv
MASS STORAGE CONFERENCE PROCEEDINGS

CONTENTS

VOLUME I - FIRST DAY- TUESDAY, JULY 23, 1991

Io Introduction ........................................................................................................... I- I

Dr. Milton Halem, Chief

NASA Space Data and Computing Division

° Enterprise Storage Report for the 1990s ................................................................ 1-3

Fred Moore, Corporate Vice President, Strategic Planning

Storage Technology Corporation

3. Optical Disk and Tape Technology ........................................................................ 1-33

Dr. Robert Freese, President, Alphatronix

4. Magnetic Disk ...................................................

Dr. John C. Mallinson, Mallinson Magnetics, Inc.

.................... 1-69

o Magnetic Tape ........................................................................................................ 1-79

L. Harriss Robinson, Manager, Mass Storage Systems

Datatape, Inc.

6. Storage System Softun:tre Solutions For High-End User Needs ............................ 1-109

Carole Hogan, Director of Technical Development, DISCOS

7. File Servers, Networking and Supercomputers .................................................... I-145

Dr. Reagan Moore, San Diego Supercomputing Center

o Mass Storage System Experiences and _tture Needs at National Center

for Atmospheric Research ..................................................................................... 1-163

Bernard T. O'Lear, Manager, Systems Programming,

Scientific Computing Division, NCAR

o The Long Hold: Storing Data At The National Archives ...................................... 1-183

Dr. Kenneth Thibodeau, Director, Center for Electronic Records,

National Archives and Records Administration

10. Banquet Presentation ............................................................................................ 1-187

Dr. John C. Mallinson, former Director of Center for Magnetic Recording

Research, University of California, San Diego
MASS STORAGE CONFERENCE PROCEEDINGS

CONTENTS (Continued)

VOLUME H - SECOND DAY- WEDNESDAY, JULY 24. 1991

I. Stewardship of Very Large Digital Data Archives ....................................................... 2-1

Patric Savage. Shell Development Company

-i zi _:iii:

2. High-Performance Storage Systems (Text Not Included in this Publication) ............ 2-7

Robert Coyne, iBM Federal Systems Research Division

Z z

3. An Open, Parallel I/0 Computer as the Platform for High-Performance,

High-Capacity Mass Storage Systems ............................................................ ............. 2-9

Adrian Abineri. APTEC Computer Systems

4. EMAssTM: An Expandable Solution for NASA Space Data Storage Needs ............. 2-21

Anthony L. Peterson. P. Larry Cardwell, E-Systems, Inc.

. Data Storage and Retrieval System ............................................................................. 2-35

Glen Nakamoto. MITRE Corporation

6. The Challenge of a Data Storage Hierarchy: Data Archiving .................................... 2-55

Michael Ruderman, Mesa Archival Systems. Inc.

7. Network Accessible Muiti-Terrabyte Archive ............................................................ 2-85

Fred Rybczynski, Metrum Information Storage

8. ICI Optical Data Storage Tape ....... ............................................................................... 2-98

Robert A. McLean, Joseph F. Duffy

o

10.

ATL Products Division's Entries into the Computer Mass Storage Marketplace ...... 2-110

Fred Zefler. Odetics Automated Tape Library (ATL)

Panel Discuss/°n: ......................................................................................................... 2-122

Moderator: Dr. Mark Kryder

Dr. Barbara Reagor, Bellc0re .... __ _ _

Darlene M. Carlson. 3M National Media Laboratory

Kazuhiro Okamoto, Sony Magneti C _gducts, Inc.

Allan S. Hadad, Ampex Recording Media Corpbration

John W. Corcoran. Consultant/Ampex Corporation

Dr. Dennis E. Speliotis, Advanced Development Corporation

!I. Poster Session::.,, ........... ,, ..... i, .... ,,..LL, ........................................................................ 2-237

Steve Atkinson. Ampex Recording Media Corporation

Barbara Matheson. STX Corporation

Kirby Collins, CONVEX Storage Systems

vi
MASS STORAGE CONFERENCE PROCEEDINGS

CONTENTS (Continued)

VOLUME 111 - THIRD DAY- THURSDAY, JULY 25, 1991

1. Tribology of Magnetic Storage Systems .................................................................. 3-I

Dr. Bharat Bhushan, Ohio State University

2. Network Issues for Large Mass Storage Requirements ........................................... 3-73

James "Newt" Perdue, Ultra Network Technologies, Inc.

3. The Role of HIPPI Switches in Mass Storage Systems; A Five Year Prospective ...3-97

T. A. Gilbert, Network Systems Corporation

, The National Space Science Data Center: An Operational Perspective ................. 3-127

Ronald Blitstein, Hughes STX Corporation/NSSDC

Dr. James L. Green, NSSDC

5. EOSDIS / DADS Requirements ................................................................................. 3-141

John Berbert, Ben Kobler

° The Preservation of Landsat Data by the National Land Remote Sensing

Archive ..................................................................................................................... 3-153

John E. Boyd, EROS Data Center

, Status of Emerging Standards for Removable Computer Storage Media and

Related Contributions of NIST ................................................................................ 3-163

Fernando L. Podio, National Institute of Standards and Technology Computer

Systems Laboratory

° Data Management in the National Oceanic and Atmospheric Administration

(NOAA) ............................................................................................. 3 - 189

William M. Callicott

9. Storage Needs in Future Supercomputer Environments ........................................ 3-211

Dr. Sam Coleman, Lawrence Livermore National Laboratory

10. Requirements for a Network Storage Service ......................................................... 3-225

Suzanne M. Kelly, Rena A. Haynes, Sandia National Laboratories

v_
MASS STORAGE CONFERENCE PROCEEDINGS

CONTENTS (Continued)

VOLUME Ill- TRANSCRIPTIONS

Introduction of Fred Moore .............. ................ 3-237

Introduction and Discussion of Dr. Robert Freese ......................................................... 3-238

Introduction and Discussion of Dr. John Mallinson ........... _......................................... 3-240

Introduction and Discussion of Mr. Harrtss RobinsOn ............... _..... _..i ._........... 3-243

Introduction and Discussion of Ms. CaroIe Hogan ......................................................... 3-245

Introduction and Discussion of Dr. Reagan Moore ...................................................... ...3-249

Introduction and Discussion of Mr. Bernard T. O'Lear ........... ' ................ _...................... 3-251

Introduction and Discussion of Dr. Kenneth Thibodeau ..3-254

Introduction of Mr. Patric Savage ........................................................................ .......... 3-258

Introduction and Discussion of Mr. Adrian Abineri ..................................................... 3-259

Introduction and Discussion of Mr. Anthony L. Peterson ........ _.................................... 3-262

Introduction and Discussion of Mr. Glen Nakamoto ...................................................... 3-265

Introduction and Discussion of Mr. Michael Ruderman ........................................ i...... 3-269

Introduction and Discussion of Mr. Fred Rybczynski .................................................. 3-270

Introduction and Discussion of Mr. Robert McLean ...................................................... 3-272

Introduction of Mr. Fred Zeiler ......................................................................... 3-275

Introduction and Discussion of Dr. Bharat Bhushan .................................................... 3-276

Introduction and Discussion of Mr. James "Newt" Perdue ............................................. 3-277

Introduction and Discussion of Mr. Tom Gilbert ........... i..... '...... .................................... 3-278

Introduction and Discussion of Mr. Ronald Blitstein .................................................... 3-279

Introduction and Discussion of Mr. John Berbert ......................................................... 3-281

Introduction and Discussion of Mr. John Boyd ............................................................. 3-282

Introduction and Discussion of Mr. Femando Podio .................................................... 3-284

Z

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VIII
N93-16321

STEWARDSHIP OF VERY LARGE DIGITAL DATA ARCHIVES

Patric Savage

Shell Development Company

Call an archive a permanent store,

Some of the largest digital data archives are operated by oil exploration

organizations. The vast bulk of these archives is seismic data. It is

kept forever because of its extremely high cost of acquisition, and

because it often cannot be re-acquired (due to cultural buildup, political

barriers, or difficult logistical/administrative factors). Western

Geophysical operates a seismic data archive in Houston consisting of more

than 725,000 reels/cartridges, typical of the industry. Oil companies

fondly refer to their seismic data troves as "family jewels."

There are relatively few "very large" digital data archives in existence.

Most business records are (gladly) expired within five or ten years

depending on statutes of limitations. And many kinds of business records

that d__ohave long lives are embedded in data bases that are continually

updated and re-issued cyclically. Also a great deal of "permanent"

business records are actually archived as microfilm, fiche, or optical

disk images their digital version being an operational convenience

rather than an archive.

So there is not really much widely known about operating digital data

archives, let alone very large ones. Even the oil companies have been in

a sense overwhelmed by this somewhat unplanned for hugeness.

This paper addresses the problems foreseen by the author in stewarding the

very large digital data archives that will accumulate during the mission

of the EOS. It focuses on the function of "shepherding" archived digital

data into an endless future.

Stewardship entails a great deal more than storing and protecting the

archive. It also includes all aspects of providing meaningful service to

the community of users (scientists) who will want to access the data. The

complete steward will:

I. Provide against loss due to physical phenomena.

2. Assure that data is not "lost" due to storage technology

obsolescence.

. Maintain data in a current formatting methodology. Also, it may be

a requirement to be able to reconstitute data to original as-received

format.

. Secure against loss or pollution of data due to accidental,

misguided, or willful software intrusion.

MD117901. PS

PRf.G_ING P_ __,_K NOT FILMED

2-1
e Prevent unauthorized electronic access to the data, including

unauthorized placement of data into the archive.

.

.

8.

Index the data in a metadatabase so that all anticipatable queries

can be served without searching through the data itself.

Provide responsive access to the metadatabase.

Provide appropriately responsive access to the data.

9. Incorporate additions and changes to the archive (and to the

metadatabase) in a timel_ way_=_ ' _ '

10. Deliver only _ of data to clients , retain physical custody of

the "official" data.

Items 4 through 10 are not discussed in this paper. However, the author

will answer questions about them at the conference or by email or

telephone.

Providing Against Loss Due to Physical Phenomena

Broadly classifying these we have:

I. Site destruction'

6

3.

4.

Theft/robbery _ _ _ :

Sabotage

Media unit suffers severe damage

5. Systemic media degradation

The first three can be guarded against, but not absolutely. The fourth is

a rare inevitable eventuality (e.g., a mechanically faulty drive "eats" a

tape.)

Systemic media degradation is best managed by using only media that are

known to have archival properties, by conservatively rewriting media that,

when accessed, are found to have an error, by regularly running PM

according to vendors' recommended practice (e.g., winding and retensioning tape), and copying the entire archive to new-generation media.

The last must be planned for, budgeted for, and be resigned to - it is an

imperative. Generally speaking, one media generation can be_eapfrogged

by the copy procedure: for example, when Shell adopted 3480 technology,

all of the 1100bpi tapes were copied; when 3490 technology is adopted, all

of the 6250bpi tapes will be copied. However, copying can be mandated

earlier if media are observed to be systemically degrading faster than

anticipated.

MDI17901. PS

2-2
Media failure occurs when an uncorrectable bit error is detected. This

always causes/implies loss of an entire error correction block -

ordinarily a minimumof one kilobyte of archived data. Archivists should

be aware that the media vendors' touted "hard error rate" always has a

10,O00-fold impact. A badly degraded media unit might have relatively

manyunreadable error correction blocks; hence even a redundancy array of

media units might then (by a little bad luck) have an unrecoverable error

correction block.

A practical cost-effective solution to the problem of protecting against

physical loss can be tailored around the following concept (which cameto

mewhile ruminating about extending the now-familiar RAIDidea to striping

tape). This is merely the seed of an idea, to which a good deal of

systems thought will have to be given.

Somenumber (in this example, 10) of archiving sites are chosen to

participate/cooperate in a redundancy scheme that provides mutual

protection against all modesof physical loss.

The sites should be geographically distributed in order to eliminate

concern that a calamity (e.g., earthquake/meteor strike) would wipe out

multiple archives. Of course, all sites individually should have

reasonably good physical security.

All sites must be accessible via state-of-the-art WANtechnology.

Each site houses, primarily, its own archive of data. (A variation would

have a single archive partitioned and distributed among its own multiple

sites.) Clients of an archive would communicate only with the primary

site.

Each site also houses either p-parity or q-parity data generated from (in

this example) 9 other sites. (Optionally two sites could be dedicated,

one for p- and the other for q-parity.)

In the eventuality of a loss at a site (of an error correction block, or

a media unit, or the site itself) any 8 of the g other sites reconstruct

the lost data. This would not be instantaneous, as with RAID, because an

extraordinary procedure would have to be executed; but the insurance would

be very certain. Clearly, each site should be practicing high quality

archiving methodology, so that losses would occur with extreme rarity

(say, no oftener than one per month).

The merits of this scheme are first, that the storage overhead for backup

can be small (25% for this example); second, that the degree of protection

can be high (with both p- and q-parity) or lower (with p-parity only);

third, independent archives do not have to create their own backup

systems, but can band together in a consortium for mutual protection.

MD117901. PS

2-3
Assuring That Data is Not _Lost w Due to Storage Technology

Obsolescence

The Ig6Ocensus was archived on the best storage medium known at the time:

UNIVAC metal tape. There was a rude awakening some years later when it

was discovered that only two drives existed in the world - one in Japan,

and the other, dismantled, in the Smithsonian.

We know now that drive technology lifetime, even assuming heroic geriatric

care, is scarcely ten years. Vendors drop maintenance after Iow'ievel

parts' technologies disappear. For a while thereafter, drives can be

cannibalized for parts; but ultimately maintenance becomes impossible.

The optical disk vendors, for example, tell of the Fine archival qualities

of their media. But their technology is evolving qu_te rapidly - vendors

come and go, and recording forma_s with them Here we have a single

medium that undoubtedly lasts a long time, but the drive and recording

technology has a half-life of less than five years. Considering the

relatively high cost of optical media, copying an archive every five years

seems out of reason.

Archiving demands that digital data on old storage technology be copied to

new storage technology periodically. The frequency depends on the media,

on how widely the drives were accepted, and on whether the old technology

satisfies current access requirements. Keeping too many generations of

storage technology in use can cause serious operational problems, even if

they are all in good working condition. For example, 556bpi tape would be

much too slow for regular use today, so, even though drives are still

available, that technology is obsolete.

Maintaining Data in a Current Formatting Methodology

The winds of C_omputation methodoiogy are ever varying. Yesterday there

was no C language. Today C-readable records might be a good bet.

Tomorrow the fad may be object files. What will come next? The curse of

required media copying iS really_a 6iessing_because it enabies _us to

continually modernize our data language. Cuneiform tablets were certainly

archival, but they contain antiquated, almost unreadable language.

Standards for "self-defining" data formats are evolving rapidly and are

already very useful. The time has come to abandon schema-less data

formats (where programs know implicitly where every field is in a record,

and what each field means).

Even fixed (schema'd) formats_are pass_ for scientific data because of the

continual change in interest and emphasis in almost every scientific

specialty.

MDII7901.PS

2-4
Archivists can extract a side benefit when copying to a new media

generation. Indeed, the planning for the copy should include deciding

which newformatting standard is to be adopted. Migrating from old to new

formats is only slightly less important for archiving as migrating from

old to newmedia technology. What's more, it's almost free.

2-5

High-Performance Storage Systems

Robert Coyne

IBM Federal Systems Research Division

Permission for this talk could not be obtained in time for the Text to be included in

these proceedings.

PRECEDING PAGE BLANK NOT FILMED

2-7

N93-16322

An Open, Parallel I/0 Computer as the Platform for H/gh-Performance,

High_apadty Mass Storage Systems

Adrian Ablneri, APTEC Computer Systems

Y. P. Che_, AVrEC Computer Systems

For those of you who are not familiar with APTEC Computer Systems, we are a

Portland, Oregon based manufacturer of I/O computers. About 400 of our systems are

installed today, typically in real-time oriented, high bandwidth environments.

Applications have included satellite ground systems, mass storage archival systems,

signal and image processing systems, etc.

Much of the discussion here today has focused on mass storage solutions

exclusively. That is high density storage media, attached to a general purpose

computer, which in turn supports network connections to users.

APTEC's focus in this environment is on programs requiring real-time data

capture, with low latency processing and storage requirements. As an example my

second introductory slide illustrates the Loral / Space Telescope - Data Archival and

Distribution System. This is an existing Loral AeroSys designed system, which utilizes

an APTEC I/O Computer.

The key attributes of a system architecture to address these types of

requirements include:

Data acquisition alternatives

A wide range of supported mass storage devices

Data processing options

Data availability through standard network connections

An overall system architecture (hardware and software designed for high

bandwidth and low latency.

The following slides outline APTEC's approach, which is designed to provide

flexible, standards based, system solutions.

I-'P,ECEDii"_G ;;A;._ BLAr_K NOT FILMED

2-9
iI

k
Aptec

A

• Introduction

Mass storage system attributes

Data acquisition

Mass storage devices

Processing options

Data availability

Architecture

• Conclusion

Introduction /Data Deluge

ERS-1

Transmits data at 100 Mbits/sec.

During this 30 minute presentation

160 9-track 6250 bpi tapes would be

filled with data.

• EOS

Expected to exceed 1 TByte/day

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2-11
A

Introduction / Loral ST-DADS

Space Telescope Data Archival and

Distribution System

VSP-1

Host

Data Ingest

I

[ ] 200 MB_tos/soc. , ]

High

Speed

: l Shared

RAID Disks SCSI SCSI SCSI SCSI

Storage Conc._ i ! i I

Cygnet Jukebox

(131) 12" Optical

858 GBytes

SCSI

I

LMSI

Distr_ution

Opticais

3.4 TBytes

Mass Storage System

Attributes

A

• Data acquisition

• Mass storage devices

• Internal processing capabilities and

connections to external processing

elements

• Data availability

• Architecture "=_

2 12 =
Data Acquisition Options

VME 50 MBytels

Bus HSI-.f,0 HIPPI

HIPPI

High Performance Parallel Interface

• ANSI Standard (X3T9.3)

• Efficient high speed interconnection

optimized for large block transfers

• Point-to-point connection

• 32-bit channel

• 100 MByte/sec simplex channel

2-13
HIPPI

Connection I

Established

L

l

Connection

Established

Packet

• • • •

• • • •

Burst J • • • •

Connection

Established

Packet

I Burst I

HIPPi _

i Specified Not

e

HIPPI Specification i_

0nly I-II_PPi channel runs at i00MB-yte/sec,

How fast the HIPPI channel is fed is not specified.

The Aptec HSl-50 1 HIPPI design provides 50 MByte/sec

sustained throughput to/from the HIPPI channel.

2-14
HIPPI (User defined ULP)

_[ Maximum Hardware Sus___tainedRate T 5 0

8 40 /sec for 1 MBytes for 16 MBytes

°;

e s

r / 2o

S for 64 KBytes R e

at c lo _1.6 MB_te/sec for4 KBytes

e i I t t

3 6 9 12 15

Block Transfer size (MBytes)

Mass Storage Devices

VME 50 MBytels

Bus HSI-50 HIPPI

High

Speed

Shared

Memory_

RAID RAID

Disks Disks

Maximum Storage

Strategy Concepts

Disk

Subsystems

D-2 D-1

Tape Tape

Ampex Sony

Tape

Subsystems

SCSI

Optical

Disks

SCSI

2-15
Maximum Strategy Disk

ii ii i i •

•!" _ n 4 Maximum Hardwar_______ee Sustaine__._ddRat____ee 44.3 MBytels_

'r M _| _ __"

• s / / 24.3_,,,_ _o_MB_

t I/ , , i , , ,

e L----I 1 1 1 _ _ t I

i 2 3 4 5 6 7 8

Block Transfer size (MBytes)

Tape Drives"

ex::Rsi _::: ::: :_±_-- :

I

AI.lind:4 MByte/sec transfer ratb_:

38 GByte capacity per cartridge

sOny-DiR 1000 (D-l)

Up to 32 MByte/sec transfer rate

12, 41, or 96 GByte capacity per cartridge

AmpexTeraSt0re (D-2) ::::i:-_ ::: i

15 MByteisec transferralS::

25, 75, or-i65 GByte _acity per cartridge _ :

Ampex TeraAccess robotic system (6.4 TByte)

2-16
Processing Options

I_P

VSP-2

VME 50 MBytefs

Bus HSI-50 HIPPI

I

RAID RAID D-2 D-1 SCSI

Disks Disks Tape Tape Optical

Maximum Storage Ampex Sony Disks

Strategy Concepts

High ]

• Speed [

Shared I

Processing Options

• HSP - High Speed Scalar Processor

20 MIP processor with 50 MByte/sec

connection to memory.

VxWorks and C.

• VSP-2 - Vector / Scalar Processor

150 MFLOP Array Processor with

50 MByte/sec connection to memory.

VxWorks, C, and Math Advantage

library of callable vector subroutines.

• Many external processor links

supported. Convex, Alliant, Sun,

Silicon Graphics, AMT/DAP, HIPPI etc.

2-17
Data Availability

HSP

I

VME

Bus

50 MBytels I

_I.-So I

, ,. i i

Network Connections

HIPPI FDDI Ethernet

High

Speed

Shared

Memory

VSP-2 RAID RAID D-2 D-i SCSI i

Disks Disks Tape Tape Optical

Maximum Storage Ampex Sony Disks

Strategy Concepts

Data Availability

Client / Server Model

TCP/IP Access

Server Software

• HIPPI

NFS Network File Access [

• FDDI

Ethernet :

2-18

=_=

R

l[

z
Architecture

Aptec architecture can sustain multiple

concurrent high data rate transfers with

predictable repeatable performance.

• Synchronous bus

• Dedicated I/0 Processors

• Real-time kernel/VxWorks with Aptec's

MultiProcessor services

Conclusion

° High performance solutions are available

today using commercial-off-the-shelf

systems and peripherals.

• They are cost effective and low risk

systems offering flexible, modular

architectures.

• Standards based.

UNIX development environment

Connectivity / networking

VME, HIPPI, FDDI, Ethernet, TCP/IP

VX/Works real-time kernel

2-19

N93-16323

EMASSTM: AN EXPANDABLE SOLUTION

FOR NASA SPACE DATA STORAGE NEEDS

Anthony L. Peterson

P. Larry Cardwell

E-Systems, Inc. Garland Division

Dallas, Texas

Abstract

The data acquisition, distribution, processing and archiving requirements of NASA and other

U. S. Government data centers present significant data management challenges that must be met in

the 1990's. The Earth Observing System (EOS) project alone is expected to generate daily data

volumes greater than 2 Terabytes (2 x 1012 Bytes). As the scientific community makes use of this

data their work product will result in larger, increasingly complex data sets to be further exploited

and managed. The challenge for data storage systems is to satisfy the initial data management

requirements with cost effective solutions that provide for planned growth. This paper describes

the expandable architecture of the E-Systems Modular Automated Storage System (EMASSTM), a

mass storage system which is designed to support NASA's data capture, storage, distribution and

management requirements into the 21 st century.

Introduction

PRECEDING

We first discuss NASA's requirements for mass storage with a focus on functional and

performance specifications. Next, an ove_'iew of the EMASS architecture is presented and

evaluated with respect to NASA's requirements. The major EMASS architectural components,

hardware, software and interfaces, are then explored with emphasis on the data management

capabilities of the EMASS software.

NASA Requirements

Requirements for large volume, mass storage systems have been well established in order to meet

the storage needs for NASA's space and Earth science information systems. The use of

sophisticated data acquisition instrumentation will continue to evolve, providing large, increasingly

complex data sets to be processed, distributed and archived. Therefore, data storage requirements

"_ir

PA_= BLANK NOT F!LMED 2-21
will continueto grownonlinearlythroughthe 1990's.For example,theEarthObservingSystem

(EOS) project alone, generating daily volumes greater than 2 Terabytes, will require automated

storage libraries with capacities greater than 500 Terabytes by the late 1990's. E-Systems is also

currently developing storage systems to meet existing U. S. Government and commercial

requirements to be delivered in 1993 having automated data storage library capacities greater than

200 Terabytes.

Data management requirements such as these within NASA and other U. S. Governmerit data

centers present significant challenges that must be met in the development of new mass storage

systems. These systems must meet increasing performance requirement s with cost effective__

solutions while providing for planned growth. E-Systems is developing the EMASS architecture

to address these requirements for extremely large, expandable data storage and data management

systems.

As we view NASA's supercomputer-based data management systems we see a need for high

bandwidth, high density tape recdrd6r systems having the data quality characteristics of a computer

peripheral. As scientific data processing requirements move towards open systems environments,

the file management software and server should support a UNIX environment. The file

management software structure should provide application specific integrated data management

solutions. A file server with high I/O bandwidth is required to accommodate simultaneous data

transfers from multiple high bandwidth tape recorder systems. Finally, to keep a perspective on

hardware and maintenance costs, the use of commercially available equipment is strongly

emphasized.

EMASS Architecture Overview

The EMASS architecture is a family of hardware and software modules which are selected and

combined to meet these data storage requirements. Fibre ! illustrates the EMASS architecture.

EMASS is a UNIX-based hierarchical file management system utilizing both magnetic disk and

tape. The storage capacity ranges from one to several thousand Terabytes depending on the type of

storage library used. it has the capabiiity to support both a graphical and metadata interface to the

user. The system is user driven by Standard UNIX and Unique EMASS commands and has user

configurable automatic file migration. The EMASS system employs standard protocols for user

file transfer_ communications and network interfaces.

2-22
Q _

.Q

i

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2-23
The EMASS system operates as a large data storage node on a network, servicing client requests

over a number of standard interfaces, including Ethernet, FDDI, DECnet, HYPERchannel TM and

UltraNet TM. The system is a two-level hierarchical data storage system. Magnetic disk is the fu'st

level of storage, and magnetic tape is the second. Data is managed via a selectable migration policy

based on data class, a method of data segregation addressed in a subsequent section. Two

alternative types of magnetic tape for data storage are included in the EMASS design: 3480 tape

cartridges and D2 digital tape cassettes. Files are migrated to 3480 or D2 tape depending on the

migration policy for the data class to which that file belongs. The physical volume repository

(Miller 1) functionality is implemented in three separate types of storage libraries which are selected

based on user requirements for performance and expandability.

EMASS Hardware

The storage system file server function is implemented in a CONVEX C3200 series computer.

The CONVEX was selected after an extensive survey of available computers. The major

evaluation factor leading to the selection of the CONVEX machine is its high I/O throughput

performance. The CONVEX supports four channels, each having I/O bandwidths of 80

Megabytes per second peak and 60 Megabytes per second average. Other key evaluation factors

included cost, compatibility with a UNIX environment, modularity, expandability, upgradability,

reliability, and support.

The file server interfaces with three types of tape libraries, the STORAGETEK (STK) 4400

Automated Cartridge System, the EMASS DataTower TM and the EMASS DataLibrary TM. The

STK tape cartrid- ge-iibrary data interface is implemented through ANSI standard Block Multiplexor

Channel interfaces Which connect to the STK 4480 drives through a SUN Library Server. The

DataTower TM and DataLibrary TM data interfaces are implemented with enhanced ANSI standard

IPI-3 tape controllers within the file server connected to E-Systems ER90 digital D2 recorders.

The DataTower and DataLibrary robotic systems provide data archive expandability. The

DataTower, with dimensions illustrated in Figure 2, serves as a medium scale storage device, with

a capacity of 6 Terabytes on 227 small D2 cassette tapes. This device was implemented by

2-24
82" T

46"

,1

t"4"-'--24" _

Recorder

Mounting

Unit

I

_'_ Storage36"Unit_1_"

Figure 2. EMASS DataTower

modifying an existing automated robotics tower currently in volume production for the broadcast

industry. The device may be expanded by adding up to three additional expansion storage units,

for a total capacity of 25 Terab.ytes.

The DataLibrary, illustrated in Figure 3, is a modular aisle architecture comprised of a series of

modules each four feet in length. This design specifically addresses the needs for a modular,

expandable data storage solution required for NASA's large data archives from EOS and Space

Station Freedom. Each shelf module contains up to 207 small, or 192 medium, D2 tape cassettes,

for a maximum capacity of 14 Terabytes. Shelf units reside in rows on either side of a selfpropelled robot and can be added incrementally as the library grows. The row of modules may be

expanded to lengths of 80 feet, providing a maximum of 288 Terabytes per row. Further

expansion is accomplished by adding additional rows and robots. Cassette access times are

specified at 45 seconds maximum for robot travel spanning an 80 foot aisle for cassette retrieval.

The DataLibrary configuration will be housed within a sealed watertight structure with interior fire

protection using CO2 supplied on demand.

2-25
i

4FT

,SHELF

ROBOT

RECORDER

Figure 3. EMASS DataLibrary

E-Systems selected D2 helical scan tape and recorder System technology to me ethigh density and

bandwidth requirements. As shown in Table 1, the 19mm D2 tape cassette is available in three

form factors: small, wlth a capacity Of 25 Gigabytes of User data, medium, with a capacity of 75

Gigabytes and large, with a capacity of 165 Gigabytes.

The suitability of the 19mm D2 helical scan media and recorder for use as a computer peripheral

has been reviewed by Wood 2. The D2 recorder provides a format already in wide use within the

broadcast industry. Ampex, SONY, and _H_iachi have dellvere'dover2_ D2 units_t0 the =':

'broadcast industry since =i988. The D2 video broadcast recorder has been m_fied to develop the

ERg0 digital recorder peripheral. Key features of the ERg0 recorder include air guides to minimize

tape wear, azimuth recording and automatic scan tracking.

2-26
The ER90 provides a sustained data rate of 15 Megabytes per second, with burst rates up to 20

Megabytes per second. Additional error detection and correction coding has been implemented

using a three-level interleaved Reed-Solomon code. Resulting error event rates of 1 in 1013 bits are

being achieved. The recorder absolute positioning velocity is 300 inches per second and logical

positioning velocity is 150 inches per second. This results in an average file access time for

mounted media of 10 seconds for D2 small cassettes and 30 seconds for D2 medium cassettes. To

provide compatibility with existing file management systems the ER90 provides ANSI 9-Track file

labeling compatibility.

PARAMETER [ 19ram - D2SPECIFICATION

Tape Media

Tape Cassette Capacities

Data Rate

Error Detection/Correction

Error Event Rate

Tape Positioning Velocity

Average File Access Time

tMounted Media)

Data Format

Peripheral Interface

25 GB (S), 75 GB (M),

15 MB/sec - Sustained

20 MB/sec - Burst

16s GB (L)

3-Level Interleaved R-S Code

1 in 1013 bits

300 in/sec - Absolute Address

10 sec - D2 Small

30 sec - D2 Medium

Compatible With

ANSI 9-Track File Labeling

Enhanced IPI Physical

(ANSI X3T9/88-82)

IPI-3 Logical (ANSI X3.147-19_)

Table 1. Recorder System Performance

The ER90 drive uses the enhanced IPI physical interface (ANSI X3T9/88-82) and the IPI-3

Magnetic Tape Command Set (ANSI X3.147-1988)at the logical interface level. The enhanced IPI

physical interface can sustain transfer rates commensurate with the basic transport performance. A

second enhanced IPI interface port can be added to allow a separate master-slave path to another

server. A large internal buffer (approximately 60 Megabytes) has been incorporated for rate

smoothing to minimize recorder start-stop sequences.

2-27
EMASS Software

The EMASS server stores files in an extended UNIX File System (UFS). EMASS software is

divided into separate components as depicted in Figure 4. These components are the user

interface, the event daemon, the mlgration manager, the file mover, and the physical device

manager. All EMASS software executes as UNIX processes at the application level. All UNIX

kernel enhancements/modifications were accomplished by CONVEX and are included in

ConvexOS TM 9.0.

Figure 4. Overview

EMASS

TAPE

N

of EMASS Software.

Users have two methods to gain access of EMASS migration services. One method is through a

user interface front-end which provides migration override control to end-users. The other method

is through direct access of the CONVEX UFS. This second method provides transparent access to

EMASS file migration services to both local and networked users.

In order to provide the ability to transparently migrate files, CONVEX has upgraded their

ConVexOS to allow the UFSt0 provide notification of selected critical file system events to a userlevel event daemon. This modification is similar to those made by the BRL/USNA Migration

Project (BUMp)3, a joint development of the US Army Ballistic Research Laboratory and the US

Naval Academy. The EMASS event daemon receives file events and forwards them to the

migration manager. The migration manager collects this information. When migration policy is

triggered, the migration manager will select files for migration and forward the list of selected files

to the file mover.

2-28

m

r

Z
The movement of files from an EMASS server disk to magnetic tape and from magnetic tape to an

EMASS server disk is controlled by the file mover. For each list of files to migrate, a file mover

process is created to perform the read and write operations. The fiie mover design provides for the

addition of software routines to support new media types.

The final major EMASS software component is the physical device manager. The physical device

manager provides a standard interface for tape movement services to all other EMASS software

components. The physical device manager will translate a generic tape movement request into the

format required by the target physical volume repository (PVR). The translated request is then sent

to the PVR for processing. The physical device manager will later receive the results from the

commanded PVR. The results are then placed into a generic format and sent to the process that

requested the tape movement. Additional PVRs will be supported by the addition of software

modules to the physical device manager.

DataClass T M

Before describing EMASS software in more detail, a discussion of the abstraction known as

DataClass TM is required. The file systems that are to be provided EMASS migration services are

subdivided at specific points in the file system tree structure by identifying those directory point(s)

beneath which all files are to be managed alike. These directory point(s), which are referred to as

migration directories, are what define each DataClass. When a new directory point is added to a

DataClass, the event daemon will request the UFS to associate the directory and all files below it

(both present and future) with the event daemon.

Figure 5 depicts a DataClass to migration directory relationship. The directory/test/dick/special is

the only migration directory in DataClass SPECIAL. All files beneath/test/dick/special will be

managed together. The DataClass PURPLE contains all files under the directories/prod/blue and

/prod/red, but none under/prod/green, showing that some directories at a certain level may be

excluded from a DataClass. All files under/test/jane and/test/dick/public belong to DataClass

TESTERS. This illustrates that the assignment of migration directories to DataClass is not

restricted to a certain level in the tree structure. In fact, migration directories from different file

systems may be in the same DataClass. Also, a file system can be mounted onto a mount point

underneath a migration directory, for example/test/jane/dirl.

2-29
Thedefinitionof DataClassiskeyto siteadministration.Migrationpolicy parametersare

configurableonaDataClassbasis,thusprovidingtheEMASSadministratorwith a greatdealof

controloverthebehaviorof theEMASSsystem.Time intervalbetweenpolicyapplication,time

requiredondiskprior to migration,anddesiredtimefor migratedfiles to remaincachedondiskare

examplesof DataClassbasedmigrationpolicy parameters.Quotasfortapeutilization(both

oo, .. ooo -'" PURP--

/X_ffESTERS . /_X U LI_

_'_./ V \_ _ greenJ

Figure 5. DataClass Example.

a warning limit and a hard limit) are also kept on a DataClass basis. DataClass based parameters

are kept in the INGRES database, so tuning can be easily done while the EMASS system is active.

EMASS software also uses DataClass as the means to segregate files on tape. All files on a tape

will be of the same DataClass. This provides a level of physical security for those sites which

might require it. This segregation also ensures that retrieval of files from different user groups (as

defined by DataClass) will not collide trying to access the same physical tape.

EMASS Interfaces

A key concept of the EMASS architecture is that it will provide multiple archival file storage

choices to the users of various networked client systems. EMASS supports connectivity over

industry standard interfaces including Ethernet, DECNet, FDDI, HYPERchannel, and UltraNet.

This provides connectivity from the smallest workstations to the largest supercomputers. The

industry standard transfer protocols available to the user include the File Transfer Protocol (FTP)
from theTCP/IPfamily, theNetworkFile System(NFS TM) as defined by Sun Microsystems, and

the UNIX utilities UNIX to UNIX copy (UUCP) and remote copy (rcp). This support is provided

by placing the EMASS interface under the Lq=S. The EMASS system will receive notification of

all managed file system events for files in every DataClass. Migration services are therefore

provided for any connectivity available on the EMASS server system to the UFS. Thus, as new

connectivity options are offered by the EMASS server vendor, the EMASS system will

automatically also provide support.

Hierarchical Data Storage

EMASS provides three levels of data storage. These three levels of hierarchical storage are

EMASS server disk, robotically managed tape, and human managed tape. When files are placed in

a DataClass, the residency is on server disk. The EMASS migration policy will schedule placing

the files onto tape based on the migration rules defined for its DataClass. The user can preempt the

migration policy by giving the EMASS system a directive to migrate specific files to tape

immediately.

When the migration policy is executed for a DataClass, all files in that DataClass which are not

solely on tape are examined. If the time since last modification (or the time since retrieval from

tape if unmodified) of a file is greater than that specified in the policy for that DataClass, then that

file's data is placed in the staging directory. If an up-to-date copy of the file is not on tape, the file

is added to a list of files to be migrated. When all files in the DataClass have been examined, the

list of files to migrate is forwarded to the file mover.

To store files on tape, the file mover first allocates tape(s) through the physical device manager.

The fries in the list are next migrated to tape. The file mover will record the location of the tape

copy of each file in the INGRES database as they are successfully written to tape. The disk copy

is left intact as a cached copy which will later be removed from disk when either 1) the length of

time since migration has exceeded its DataClass defined limit or 2) the file system requires

additional disk data blocks and it is the oldest staged file on disk. When the file mover has

completed migrating files to tape, the tape and drive are released back to the physical device

manager.

Not removing disk data blocks from the staging directory on strictly a first-in-first-out basis

provides additional flexibility. A file system can be divided into DataClasses which can have

different access requirements. Each DataClass will have its own disk retention period, so one

2-31
portionof afile systemcanhavedatathatis notcachedondiskaslong asanotherportion. One

DataClassthuscanbesetupto neverfreediskdatablocksexceptwhenrequiredto provideneeded

freedisk spaceforthefile system.

WhentheUFSreceivesa requestfor datablOcksfor afile Whichisnotcurrentlyondisk,the

requestingprocessis suspendedandtheEMASSeventdaemonis notified. Theeventdaemon

forwardsthatnotificationto themigrationmanagerwhichimmediatelyinstructsthefile moverto

retrievetherequestedfile to disk. The file mover requests the tape containing the file be mounted

and copies the file to disk. The requesting process is now allowed to continue processing. The

EMASS system maintains knowledge of the tape copy. If the disk copy is unchanged, the file will

not be re-migrated by the migration policy.

The retrieval of a user-directed range of bytes from a file is also available to the EMASS user. This

is accomplished much like the retrieval of a complete file. However, the file mover will copy the

specified range of bytes into a UNIX file of a different name as specified by the user. Thus, the

user can retrieve only the portion of the file of interest, reducing the amount of data brought back.

The EMASS system will also manage tapes that are not under robotic control. This will allow sites

to have EMASS management of many more tapes than the robotic system can support. When

access is requested for a file that is only on a tape that is not under robotic control, the EMASS

system will request the operator to return the tape to active service so that the file may be copied

onto disk. The effect to the user is only a longer delay waiting for a tape mount.

Infinite File Life

A mass storage system must provide for the integrity of its client's dam. In order to insure that the

client's data is always available, the EMASS system has several features to provide safeguards

against data loss. These features include automatic Error Detection and Correction (EDAC)

monitoring and secondary file copy maintenance.

For every file segment written by an ER90 drive, the drive will automatically perform a read while

write comparison. If the data written is not recoverable or to successfully recover the data written

required more than a minimum threshold of correction, that segment is automatically re-written to

tape by the drive Without any action required by the host system. This provides positive assurance

that the data written is retrievable without much stress on the EDAC at the time it is recorded.

2-32
Foreveryfile readby anER90drive,theEMASSsystemwill requesthedrive to returnEDAC

statisticsandif thelevelof correctionwasexcessive,thattapewill beplacedin a"suspect"list for

systemadministratoraction.ThesystemadministratorcanthenatalatertimerequestheEMASS

systemto moveall filesoff of theold tape.This providesforrefreshingtheEDAC encodingfor

all flies thatwereontheold tape.

To ensurethehealthof D2 tapesthathavenotbeenaccessedfor awhile,theEMASSsystem

providesatapesniffing service.Tapesniffing is theprocessof periodicmonitoringof tapesthat

havenotbeenaccessedfor alengthof timedefinedby thedatacenter.TheEMASSsystemwill

schedulethereadingof samplefiles from thetapeandthenexaminetheEDAC statisticsto

determineif thelevelof correctionwasexcessive.If excessive,thetapeis pIacedin the"suspect"

list for systemadministratoraction.

As anaddedmeasureof protectionfor tape-basedfiles, secondaryfile copyingisprovided. If

enabledfor itsDataClass,fileswill automaticallyhaveasecondarycopymaintainedonaseparate

tape.ThisDataClassfeaturecanbeoverriddenona file basis,thusallowingtheuserto requesta

secondarycopybecreatedwhentheDataClassdefaultisto notmaintainacopy. Theusercan

converselyrequestheEMASSsystemnotto maintaina secondarycopyof a file whenits

DataClassdefaultis to maintainacopy.

Throughtheuseof automaticEDAC monitoringandsecondarycopies,theEMASSsystem

providesfor theintegrityof its client'sdata. Thelife of theEMASSclient'sdatacanin factbe

prolongedwell beyondthatof anyonetypeof storagemedia,asthefile sniffing servicewill

promotedatafrom onemediaontoanother.

Summary

EMASS software provides a UNIX-based data storage solution with automatic and transparent file

migration and retrieval. Data archive centers can be provided with very large (up to Petabytes),

expandable, automated data storage systems. These data storage systems connect to high speed

networks, providing 24 hour per day accessibility for rapid delivery of requested data in the Space

Station and EOS era. File access can be provided to networked users through standard file transfer

protocols. A graphical user interface can also be provided. Thus, the client is not required to have

special networking software. The implementation of DataClass provides a flexible method for

tuning the behavior of the system at each installed center.

2-33
Trademarks

EMASS, DataTower, DataLibrary and DataClass are trademarks of E-Systems, Inc.

CONVEX and ConvexOS are trademarks of CONVEX Computer Corporation.

UNIX is a trademark of AT&T.

INGRES is a trademark of ASK Computer Systems.

NFS is a trademark of Sun Microsystems, Inc.

HYPERchannel is a trademark of Network Systems Corporation.

UltraNet is a trademark of Ultra Network Technologies, Inc.

References

1 S.W. Miller, "A Reference Model for Mass Storage Systems", Advances in Computers, Vol. 27,

Academic Press, 1988, pp. 157-210.

2 Tracy G. Wood, "A Survey of DCRSi and D2 Technology", Digest of Papers, Proc. Tenth IEEE

Symposium on Mass Storage Systems, May 1990, p. 46 (1990).

3 Michael John Muuss, Terry Slattery, and Donald F. Merritt, "BUMP, the BRL/USNA Migration

Project", Unix and Supercomputers, 1988.

2-34
Data Storage

and

Retrieval System

24 July 1991

Glen Nakamoto

MITRE Corporation

Bedford, MA 01730

(617) 271-3032

2-35
m_

L_

m_m
Data Storage and Retrieval

N93-

System

16324

The Data Storage and Retrieval System (DSRS) consists of off-the-shelf system

components integrated as a file server supporting very large fries. These fdes are on the

order of one gigabyte of data per f'rie, although smaller fries on the order of one megabyte

can be accommodated as well. For instance, one gigabyte of data occupies approximately

six 9 track tape reels (recorded at 6250 bpi). Due to this large volume of media, it was

desirable to "shrink" the size of the proposed media to a single portable cassette. In

addition to large size, a key requirement was that the data needs to be transferred to a (VME

based) workstation at very high data rates. One gigabyte (GB) of data needed to be

transferred from an archiveable media on a file server to a workstation in less than 5

minutes. Equivalent size, on-line data needed to be transferred in less than 3 minutes.

These requirements imply effective transfer rates on the order of four to eight megabytes

per second (4-8 MB/s). The DSRS also needed to be able to send and receive data from a

variety of other sources accessible from an Ethernet local area network.

System Configuration

In order to meet these requirements, a system was configured using Aptec's

Input/Output Computer (IOC-24) with Storage Concepts C51 disk array and Honeywelrs

Very Large Data Store (VLDS) tape drive (dual channel unit) as the basic components for

this file server. The IOC-24 has eight megabytes of shared memory and was hosted on a

VAX 11H50 which, in turn, was connected to an Ethernet local area network (LAN). The

interface to the VME based workstation was accomplished via Aptec's VME Gateway

Controller. The specific (and initial) VME based workstation that needed to be interfaced

for this project was the Sun 3/260 workstation containing a Vicom II-9 image computer and

the Vicom Fast Disk (Maximum Strategy's parallel disk array). The Sun workstation also

contained a 16 megabyte high speed (32 MB/s) memory card from Micro Memory. This

memory card was used as a high speed receiver (or transmitter) of data during the initial

period (prior to the Vicom Fast Disk becoming available) for debugging purposes. Data

needed to be transferred to/from the DSRS file server (C51 disk or VLDS tape) to the

parallel disk array under the control of the Sun workstation operating at the data rates

previously discussed. The specific configuration is illustrated in Figure 1.

PRECEDING PAGE BLAN_ NOT FILMED

2-37
ool

VIA3S

Tape

Drive

O

9-Track

Tape

Drive

Disk

Drives

/

C51

Disk

Array

!T

VAX

Host

I/O

Computer

Ethemet

Other

Devices

[3--

VME I Sun I

GC t Workstation

I

I n

Vic°m [ I Vic°m II-9 I

Fast Image

Disk Computer

Figure 1. Data Storage and Retrieval System

Component Performan¢¢

From a performance standpoint, the C51 disk is the fastest peripheral on the DSRS.

It has been measured as transferring (across the VMEbus to high speed memory) in excess

of 9 MB/s using transfer block size of one megabyte. The transfer block size is critical in

determining the effective transfer rate. Figure 2 shows how the effective transfer rate

varies with the block size used when transferring data from the C51 to the Vicom Fast Disk

(C512FD) or vice versa (FD2C51). These transfers were done using files on the order of

500 M bytes 0 f dam-_ F0r_th_e DSRS applicat!on, ablock sizeof two megabytes (512 K

words) was chosen. This final size was dictated more by the Vicom Fast Disk rather than

the C51 disk. For this configuration, the C51 disk array has 2.5 gigabytes of formatted

disk space.

2-38

!
M

B

Y

t

e

S

/

S

e

C

16K

I I I |

32K 64K 128K 256K

Trans_rBlockSizein4B_esWo_s

C512FD-._. o.. FD2C51

Figu_ 2. Trans_rRateasaFuncdonofBlockSize

I

512K

The VLDS is a streaming tape drive and streams data at approximately 4 MB/s.

Since it cannot start/stop like a conventional tape drive, it is imperative that it operate at its

full transfer rate. In the read/playback mode, the VLDS can stop/restart taking

approximately eight seconds to restart. Any significant mismatch in transfer rates between

the VLDS and another device could slow the overall transfer rate down to eight kilobytes

per second (KB/s). On the write/record side of the transfer, the VLDS will write "padding

blocks" while continuing to stream. However, there is a maximum number of padding

blocks that is (user) specified prior to the system halting (i.e., no restart). VLDS tapes that

have padding blocks will have a natural degradation in transfer rate as well as in tape

capacity. With no padding blocks, one VLDS cassette (super VHS T-120 cassette) will

store approximately 5.2 gigabytes.

2-39
TheVME gatewaycontrollercaneffectivelymovedatafrom theIOC'sshared

memoryto theVMEbusontheworkstationatratesin excessof 11MB/s. Thetransferrate

alsovariesasa functionof block sizeasshownin Figure3. Thesetransferrateswere

10

M

8

B

e 6

S

/

S

e 4

C

2

0

Illilllllllllllllllllllllillllllllilllllillillllllllllllllll

I 'I I I I l I I I

.25K .SK 1K 2K 4K 8K 16K 32K 64K 128K

Transfer Block Size in 32-bit Words

Figure 3. VME Transfer Rate as a Function of Block Size

obtained using the VME gateway controller in the Master mode. In the final configuration

of the DSRS, the _ gateway controller is used in the Slave mode. Experience to date

indicates that Slave mode transfer performance is similar to Master mode operation. For

Sun 3/2XX workstations, the CPU exhibits a 190 microsecond bus timeout. This means

that the V_ GC Cannot hold/.he bus longer than 190 microseconds after the CPU asks for

it else it times out and the Sun operat_g system (SunOS)crashes. Since the VME GC

operates in a release-when-done (RWD) mode versus release-on-request (ROR), it holds

E

2-40
thebusfor theentiretransfer.Thispracticallylimits themaximumblock sizeto underone

kilowords in Master mode operation (in order to stay under the 190 microsecond time

limit). This limitation was overcome by using the VME GC in Slave mode and using a fast

master controller (Maximum Strategy disk controller) operating in a ROR mode to effect the

high speed transfer.

While not part of the DSRS, the Vicom Fast Disk is the other key device when

examining end-to-end file data transfer. The Vicom Fast Disk is actually a disk array made

by Maximum Strategy, Inc. (Strategy One Controller). In this configuration, the disk array

contained approximately 6 GB of formatted space. The hardware is unchanged from the

original product. However, Vicom has written a device driver and a file management

system for it. The Vicom Fast Disk was rated at running at eight MB/s. While Vicom

literature indicates 12 MB/s burst and eight MB/s sustained, in reality, 12 MB/s burst only

occurs during the first megabyte of data (since it comes from memory and not the disk

array). The eight MB/s sustained rate applies to the transfer once the disk heads are in

position and is "streaming" data. In reality, large block sizes were needed to maintain

transfer rates near eight MB/s.

While all the hardware components were available off-the-shelf, no software was

available to allow the components to function as a system. The key integration task was to

develop the software and ensure that device performance would not be impeded by this

software. A key challenge was to ensure that the VLDS tape unit operated at its full 4 MB/s

capacity since it functions as a streaming tape drive. As indicated earlier, running the

VLDS at slower than 4 MB/s would significantly slow down the total transfer time.

Paramount to the development effort was to keep all overhead to an absolute minimum.

Another challenge was to keep all software development at a high level - not develop any

assembly language or microcode. Efficient use of library routines was essential. In order

to promote a high level of portability, all routines developed on the Sun workstation had to

be written in the C language and interfaced to existing Vicom device drivers. No kernel

modifications were allowed as well. Since the software effectively controlled key hardware

components directly, it was extremely difficult to debug since the typical error message was

"bus error" (followed by a system crash). The use of a bus logic analyzer was essential to

do problem identification and debugging. During this development effort, several key

problems were discovered and f'Lxed on the VME gateway controller. All problems dealt

2-41
with theuseof theVME GC in slavemodeoperatingat high(-12 MB/sec)speeds.

Softwaremodificationsat themicrocodelevel(in Aptec'ssoftware)werealsomadeto get

thesystemoperatingproperly. Thesechangeshavenow beenincorporatedaspartof

Aptec'sbaseline.

VLDS TaR Unit

The VLDS was the first peripheral to be interfaced to the IOC-24. By using a dual

buffering scheme to keep data transferring between the VLDS and the shared memory, the

effective transfer rate of 4 MB/s was easily maintained when sending data to the IOC's

memory. When the VME gateway controller (VME GC) was added to the IOC, data was

then made to flow from the VLDS, to the shared memory, to the VME GC Input/Output

Processor (IOP), to the VME GC, and then on to a high speed memory card on Sun 3/260

workstation with no delays. Later when the Vicom Fast Disk was added to the Sun

workstation, itbec_apparent that the Fast Disk needed large (one megabyte or larger)

transfer blocks in order to maintain high throughpui. Since the VLDSreads and writes in

principal block increments of 65,536 bytes (64 KB), a buffer size mismatch needed to be

fixed. The dual buffering scheme had to be modified to accommodate 64 KB buffers on

the VLDS side and 2 MB buffer size on the VME/Vicom side. This was accomplished by

using multiple VLD$ buffers adding up to the (two MB) VME side buffer, then taking into

account partial buffers and iast buffer anomalies. Wi_ this approach, it became possible to

transfer fries from slow devices such as the Sun local disk to/from the VLDS at high data

=

rates (as fast as the slowest device) for f'des up to 2 megabytes in size with no degradation

in performance. Largerfrie s could also be sent but the VLDS start/stop action would cause

a degradation in performance.

C51 Disk Array

Interfacing the C51 :_sk array into the DSRS involved making a key decision

regarding its use. The C51 could be used in a dedicated manner, i.e., used by a single

process until completed, or shared like a disk server. Used in a dedicated manner, the

performance would be optimized and the software would be easier to develop. The major

drawbacks were that the disk array would not be shareable between processes and only

contiguous fries wou/(i-'be supported' This last condition was quite restrictive when there is

2.5 GB of disk space and frie sizes of one to two GB could be expected. The contiguous

requirement would prevent files from being written even though the space may exist due to

i

2-42

E

ie
disk fragmentation or possibly bad disk blocks/sectors. The DSRS configuration uses the

more complex VAX/VMS file management system (QIO) to create and manipulate f'des on

the disk array. This allows files to be written out with multiple extents if needed. Another

advantage of this approach is that the disk subsystem is shareable by different processes.

Thus, a lengthy transfer that may take 3 minutes can function at the same time that another

user is accessing a small fde on the same disk, without having to walt for the f'trst transfer

to complete. From a VAX user viewpoint, the C51 appears as a standard disk (though

non-system bootable) and functions, such as file transfer (ftp) and copy, can be used to

transfer data from VAX based peripherals or other peripherals attached via the Ethemet

LAN. Transfers involving the C51 also use a similar dual buffering scheme to maximize

the transfer to/from the IOC's shared memory then on to the destination device.

VME Gateway Controller

The VME GC was, by far, the most challenging piece of equipment to understand

and integrate into the system. A series of protocols were developed to allow the DSRS to

communicate with the target workstation. The fast protocol (command protocol) involved

sending a command and appropriate parameters from the Sun workstation indicating what

transfer needed to be done with what files. The second protocol (information protocol)

involved communicating information regarding file size, transfer block size, and size of the

last transfer. This information was critical to ensure both sides (DSRS and workstation)

knew exactly what and how much data was being sent. Finally, the transfer protocol

involved the low level "handshaking" needed to keep the data transferred in proper

synchronization, i.e., ensure that source and destination devices were ready to receive the

appropriate blocks of data. From an ISO networking viewpoint, these protocols fall into

the application layer. They effectively establish a means of communications at a high level

between a workstation and the file server (DSRS) for the transfer of a file. From a logical

viewpoint, the VME GC is set up like a data structure featuring a ftrst-in-ftrst-out (FIFO)

location, a mailbox area for small messages, and a set of 16 registers. The base address to

this logical structure is user programmable and can exist anywhere within the workstation's

memory space. Physically, the VME GC is also user prograrnrnable and can exist

anywhere within the VMEbus 32-bit address space (barfing conflicts with existing

devices). The FIFO is used to transfer large blocks of data between the workstation and

the DSRS. The mailbox region is used to pass file names, file sizes, and other

miscellaneous pieces of information. The registers perform all control functions including

setting the direction of transfer, number of bits per word, FIFO full/empty indication,

2-43
semaphoreacknowledgements,etc. The DSRSis setupwith apredefineddatastructure.

TheSunworkstationalsoseesthissamedatastructureandcommunicateswith theDSRS

byreadingandwriting to thesememorylocationsasif theDSRSwaslocal to it. By using

thisapproach,differentVME basedworkstationscanbeintegratedwith the DSRS with

minimal diffiCulty. All that is needed is an understanding of how to memory map to a

specific memory location and a VME memory device driver (both commonly standard with

any w0rkstation/operating system). An interface guideline document describing both the

hardware interface requirements (for the_ GC board set) as Well as a detailed

description of the above protocols (for a software interface) has been published.

Typical Data How (C51 to Vicom Fast Disk)

Once a user on the Sun workstation "launches" a transfer function, the VME lOP

spawns a request to the C51 lOP to initiate the file transfer. Four megabytes of shared

memory (organized as two 2 MB buffers) are allocated in the IOC. The C51 IOP's task is

to fill each 2 MB buffer and mark the empty semaphore flags as "full" upon completion of

writing a buffer. At the same; time, the VME IOP reads the same buffers (when the

semaphore indicates that the buffer is "full") and flags the buffer "empty" upon completion

of the read function. The two processes run ¢,9.nc..ai:/:r,aI_ switching buffers as necessary to

keep a steady flow of data moving, _en the VME lOP reads the 2 MB buffer, the data is

simultaneously transferred to the VME GC which has previously initiated "handshaking"

with flae sun W6rksiation CPU. intfiemeantime, the sun CPU has transferred control to

the Vicom Fast Disk controller which masters control of the VMEbus and extracts the 2 MB

of data from the (FIFO address location of the) _ GC and _sfers the data to its input

buffer and subsequently to the disk array.

This single cycle which involves transferring data across three busses (DIB,

OPENbus, and VMEbus) with "handshaking" and resource arbitration is executed 500

times ( to transfer a gigabyte of data) and runs at 96% of the maximum burst Speed of the

slowest link.

Software Architecture

The software on the VAX was set up as a single program running as a server

listening to commands (via a semaphore register) that it might receive from the Sun

workstation. In actuality, the VME IOP has software constantly checking one of the

2-44

=

F

E

i

J

I

E

L
registers to determine if a workstation wants to deposit a command into the mailbox. Once

a command is received, the VME IOP is allocated and cannot be used by another device

until the command has been completed. The VME IOP "downloads" the appropriate code

and executes all transfer routines or spawns appropriate routines to accomplish the

commands. Upon completion, the semaphore register is setup for the next request. During

the transfer of information, if any substantial delays occur, either side will timeout and

revert back to listening mode. This allowsthe server software to recover from errors that

may occur on the workstation. Using this approach with multiple VME IOPs and VME

GCs would allow multiple VME based workstations to access the DSRS resources in

parallel, limited only by the device speeds, the amount of shared memory, or bus

bandwidth within the IOC-24. Over 60 STAPLE routines/procedures were written to

support this server software.

The software on the Sun workstation was written as a series of short C routines that

effect a transfer from one device to another. A typical routine name was vlds2fd implying

(in this case) transfer of data from the VLDS to the Vicom Fast Disk (FD). Following the

command, the source and destination file names would be included as parameters. Ten of

these routines were developed to transfer data in all conceivable directions. Over 30

routines/procedures were written to support the Sun based software.

Due to the development environn_nt and the tools that were. available, the entire

system integration and software development effort for the DSRS took less than four

months (with a staff of two)'. Interfacing the Sun/Vicom system took an additional two

months (although hardware problems precluded use of the system for almost half of that

time).

Conclusion

In the end, the DSRS successfully transferred one gigabyte of data from the VLDS

to the Sun/Vicom Fast Disk in 4 min. 13 sec. + 25 sec. for tape setup and rewind. This

translates to an effective transfer rate of 4 MB/s during the transfer (which is the streaming

rate for the VLDS). The file transfer from the C51 disk array to the Sun/Vicom Fast Disk

took 2 min. 15 see. using 2 MB transfer blocks. This translates to an effective transfer rate

of 7.7 MB/s (out of a theoretical maximum rate of 8 MB/s as constrained by the Vicom Fast

Disk). File transfer was also performed between the C51 disk array and a device (a local

disk attached to another Sun workstation) over Ethernet while, at the same time,

2-45
transferringa file from the Vicom Fast Disk to the C51. Although the performance was

slightly degraded due to the sharing of the C51 disk, it was not noticeable using small files

(less than 10 megabytes).

All requirements were fulfilled using commercially available off-the-shelf

components with a relatively small software development effort. The system is now

operational and is being used to Store and retrieve large files on VHS cassette tapes and can

load the Sun workstation (Vicom Fasi _sk) in minutes versus the many hours it used to

take when using 9 track tapes.

, 2

2-46

i

|

i

m

_i

m

I

h
Data Storage

and

Retrieval System

Glen Nakamoto

24 July 1991

Background

Concept of Operations

....................................... j

[_sk i

......... _;. ............. T

and Retrieval _

System (DSRS)

• Support evaluation of operationally-oriented softcopy imagery exploitation

• Two sessions per day; four hours per session

• Preload images into workstation prior to session

• Ad Hoc access to any image stored on the server

MITRE

2-47
A Key Problem

5 In.

12 In.

22 Nine-lrack Tapes One VHS Tape

15 Hours Input Time 10 Minutes Input Time

*L

FY90 Goal

• Develop a prototype data storage and retrieval system

- Support Image files 20 - 30 times larger using single

portable media

' Transfer files at rates g0 times current _pabili_ _ i:i ----

• Establish interface guidelines for future workstations •

- Multiple standards (Physical, networking, application)

- Portable media (Tape, format)

• Interface initial commercial workstation

E

M,TRE p

2-48

=
DSRS Architecture

VHS

Cassette

Tape

Ethernet LAN

5,200 MBytes _ _.

32 Mbps

I VLDS* I

Tape I

Drl;e I

I

C51 *

Disk

Array

2,500 MBytes

80 Mbps

High

Speed

Image

Source

Planned I/F

I

Electronic

Light Table

Workstation

Electronic _@ Light Table

Workstation

i

Electronic

Light Table

Workstation

Data transferred at rates

up to 80 M blts/sec vla

dlrect VME interface

"These itemslit in a rack

space of 27 inches.

Electronic Light Table Workstation

_., Hiah Soeed

" Interface

Ethemet LAN

Workstation Sun4

] 16 Parallel Processors

6.0 Gbyte capacity

64 Mbps transfer rate

• Electronic Light Table Functions

• Integrated Database -

Text, Graphics, Imagery

• Large Image File Manipulation

• Real-time Decompression

• 2K by 2K display size (search)

• High Speed Image Transfer

(64 Mbps)

• Off-the-Shelf Hardware

PreviouslyPixar

2-49
Image Server Configuration

Sun

HD-96 ..91. EIm:_oN¢ T Drive Llflhl Tab_ I -JQ

: MOTRE

: Software Architecture ........... .

MlctoVa= 3500 /t_

(.os, c_u) _: _oo,,,_:__/;

\ C.o.oc,o_- t " I.°

Unibus Serverside "_ _"

us _. _VMEbus|Read,romVME ['

" Gateway L

_rlOP0 CPU_ C°ntr°l _ |W"tet°_D' _F I _

J-_'bL5 _ OPF:"bu$ "NN'N ; IN'

lOP1 CPU ' ' _ lOP2 CPU _ _ VME Gatewav I _/

& \ | f_ Read from Device Read tom Memory FIFO Buffer

_,e ,o Me_ _i _dte to VME Gateway Mailbox

I Memory organized'

I as dual buffer (8 MB)

E

2-50 =
Measured Transfer Rates

Network

Ethemet 10 Mbps

FDDI 100 Mbps

UltraNet 125 Mbps

DSRS 96 Mbps

IOC 100 Mbps

based

FDDI

Effective Throuohout

2.4 Mbps

2.5 Mbps

20.0 Mbps

93.6 Mbps

48.0 Mbps (not measured)

Notes:

Sun memory to Sun memory transfer with no network contention.

SunOS 4.1 (Sun 3/260 with 8 MB memory).

Sun provided TCP/IP software.

UltraNet used TP4/IP with board level ixotocol processing.

MITRE

C51-PFD: Transfer Rate vs. Block Size

7

M e

B

¢

s 4

!

s 3

e

e 2

1

0

16K

i i i i a

32K 64t( 128K 2S6K 512K

Transfer Block Size in 4 Byte Words

C512FD 4,- 4]- FD2CSI

MITRE

2-51
VME-MM Transfer Rate

12

10

M

13 8

Y

t

¢

6

$

/

$

e 4

¢

0 _ J t I | ! I

,25K .5K IK 2K 4K 8K 16K 32K 64K 128K |

Transfer Block Size in4 Byte Words ie

MITRE

i

• Requirements for DSRS finalized in September 1989

• IOC based system purchased in October 1989

• System delivered on 18 January 1990

• The DSRS was developed and delivered i8 June 1990

• Integration of the Sun/Pixar workstation was completed

by 9 August 1990

• Improves transfer times 90:1

• Improves storage approximately 100:1

• Allows search oriented experiments to be conducted

• Improves the management of an image library

• Promote standards and interface guidelines

MITRE

2-52
FY91 Goal

• Integrate an FDDI network into the DSRS

- Develop an FDDI gateway for the DSRS

- Initially support TCP/IP protocols

- Provide capability to install other protocols

- Provide capability to support multiple gateways per IOC

- Maintain maximum performance end-to-end

• Upgrade IOC-24 to IOC-100

• Upgrade 2.5 GB Disk Array to 7.5 GB capacity

- Provide means to address greater than 32 bits

MITRE

2-53
!

iE

m_
CHAT.T_NGE OF A DATA STOR/_-_ FrrERARCHY

Mr. Michael Ruderman

Vice President for Marketing

Mesa Archival Systems, Inc.

N93-16325

MR. RUDERMAN: Good morning. I have the pleasure of standing between you and

lunch. So, I will try and speak quickly and get through as much of this material as we can.

I'll tell you a little bit about Mesa Archival Systems first.

We are a small private company located in Boulder, Colorado. We were founded as a

technology spin-off of software originally developed at NCAR, the National Center for

Atmospheric Research. Currently, their version of this software is managing 19 terabytes

of data on over 102,000 3480 cartridges. They are in the process of moving from 3480 to

3490 tape cartridges, but it is clear that this represents a large amount of data from a

variety of systems and is composed of fairly large set of biffiles.

Something else you ought to know about Mesa Archival is that we are part of the

winning team of the recent NASA Goddard mass storage award that hopefully, barring any

obstacles--legal or otherwise--you will all be able to see running here at NASA Goddard in

the next couple of months. We are looking forward to that. (Showing of viewgraphs)

MR. RUDERMAN: Now, before going into the storage hierarchy aspect of the system, I will

put it in some perspective with a brief overview. What is the system in general?

It is a data archiving system; it fits into the kinds of environments that all of you

have or are working towards, whether you are vendors or users, with multiple

heterogeneous client systems networked to a central archive server.

That is the simple explanation.

(Change of viewgraph)

MR. RUDERMAN: We can picture our system, as illustrated. Obviously, any kind of

client system on the network can be connected through the Unix interface of our system. We

are strictly a software system sitting on a mainframe, managing the data into permanent

file storage. We do not have time today to go into all the details of how we do everything. But

suffice it to say, it is a central archive manager, with standard network access and it is a

standard commercial product--that is very important.

We came from a lab environment; however the version that is now available is not

lab code. It is commercial product code. It sits in a high-performance computer, accessible

from multiple processors.

(Change of viewgraph)

MR. RUDERMAN: And Just to reiterate, when we took this code from NCAR and

designed it for commerciality, it had to be designed for change. Much of what you are

hearing during this conference is a lot of information, from both users and suppliers, about

a lot changes taking place in the area of mass storage devices.

We believe one of the most important ideas to keep in mind is that data must outlive

any device or any media; the data is more important than any of those things.

The hardware is going to keep changing; and so, you have to have a software control

system that is independent of any hardware system. We believe in that.

(Change of viewgraph)

PRECEDING P.(_IGE ELAI'_K NOT FILED

2-55
MR. RUDERMAN:Let'stake a look at the next levelinto the system. As I said,we

support standard networks,TCP/IPwith FTPaccessand NETEXwith UserAccessclient

support. We put no code on client systems. The network access server provides the access;

the data library access manager provides all the client and system communication

dialogue. As demand warrants, support of additional new network protocols will be added

easily.

The archival object database is the heart of the system, and here we have

implemented our own object oriented analysis. At the back end of the system there are

multiple storage servers, and of course, system administration. This is where we will focus

on a little more detail.

Before getting into that, I want to mention that we are an active member of the IEEE

Mass Storage Reference Committee and Storage Subsystem Working Group, - we have been

involved with it from the very, very beginning. In fact, NCAR was one of the originators of

the whole idea back in the mid-1980s.

(Change of viewgraph)

MR. RUDERMAN: This is our version of the IEEE components model, and what I

want to talk about today is the storage system side of it. AS you can see, we have separate

data paths between bitfile movers--the bit movers from the client side and the server side--

and here we have multiple storage servers, which is the area that we want to look at. The

issue is how do we implement that?

(Change of viewgraph)

MR. RUDERMAN: With the variety of devices available--and you have all been

hearing about a whole bunch of them in the last couple of days--the variations cover access

speed, permanent versus temporary storage, capacity, cost--cost is a major factor.

I think half ofy6u Could go home--tho_ ofy6u who are hardware vendors--ff there

were infinite rotating disk storage available at a very low price, we probably wouldn't be

worrying about this conference too much. Life would be simple, but it's not that way.

And products keep changing. What may seem like simple changes from 3480 to 3490

technology have implications--big implications. New products--D-1, D-2, optical disk,

optical tape, etc.. Our objective on the software side is to keep the data independent of any of

these hardware changes.

(Change of viewgraph)

MR. RUDERMAN: Now, this morning, you heard Bob Coyne from IBM talk about the

storage hierarchy and the issues and problems of a static storage hierarchy. Because there

are now multiple devices being implemented in single archives, both for cost reasons,

technical reasons, and user reasons, the traditional, what we call "static hierarchy" of

primary and secondary storage alternatives, is just not sufficient.

The problem surfaces as soon as you try to figure out what you do with the third one

you want to add--the third type of storage de_ce. Where do you put it in the hierarchy? For

different kinds of data it belongs in different places.

We have examined this; we have spent a fair amount of time on this over the past

year or so. To say that we have solved it, is easy. What we Will try and show you is how--the

conceptual approach as to how we solved it. This is, in fact, what is available from Mesa

Archival Systems today.

(Change of viewgraph)

2-56
MI_ RUDERMAN: To give you a feelingfor what I'm talking about a little more

specifically,wecan seethat from the data library system,we can support magneticdisk,

optical disk, cartridge tape, helical scan magnetic tape--all of these kinds of storage

devices,multlple devices,heterogeneousdevices--simultaneously.

You cannot do that very efficiently with the traditional static hierarchy of a fixed

physicalsystem. So,wehavedevelopeda structured hierarchy, whichgivesmultiple views

of thosephysicalstorageoptions. It is dynamic,andit must be ableto bevariedby user,by

bitfile--down to the bitffle level--by class of data, by accounts, by any combination of

categoriesto bederivedfor eachsystem.

Now,that is aneasything to say,but it's not soeasyto implement. LetmeJust make

a note. I seesomeof you lookingthrough the proceedingsand not necessarilyfinding all

the slides identical. We recently updated someof these and createdsomenew onesfor

today;and I apologizefor any confusion.

We didn't get them sent in. but we will get a new set available for the followon

proceedingsbook. So, you might as well Just ignore what's in there at the moment.

(Changeof viewgraph)

MR.RUDERMAN: It'seasyto say,not soeasyto do.

The first thing we did is separatethe archive system from the storage system

conceptually. Bitfiles comeinto the system.Therecan be one or more imagesof them,

dependinguponthe attributesofthebifffle. Youmaywantto keepa copyon disk,put a copy

onoptical;you maywant to keepcopies on multiple devices for various reasons.

Each image of a bitfile, unless it is very small, will have multiple fragments; and

these fragments reside on specific types of media. The media gets broken down further into

packages and surfaces. I'll show you later how that all flts together.

But basically, the first thing to do is to separate the archive system from the storage

system and implement the whole concept from the point of view of object-oriented analysis

and design.

That makes the use of it simple; it makes the coding of it not so simple, but it has

been accomplished.

(Change of viewgraph)

MR. RUDERMAN: Now, let's take a look at this from an object orientation. We have

a client file in the system. This cllent file talks to the bitfile server, requesting services.

The bitflle to be archived will request storage from various storage options. Here we

are Just showing two; there can be any number of storage options based upon what the

physical system has installed.

(Change of viewgraph)

MIL RUDERMAN: As we take a look at this, we see the kinds of objects that sit under

each of these categories. In the client file system we have the directories and flies and users

and groups. The bitflle archive has the bitfiles and accounts that they belong to, ff that is

appropriate, and the templates.

The templates are very important. The templates describe which of the storage

options are available for a particular bitfile or, in other words, which of the options that

2-57
arephysically on the systemare the permitted options in this instance. In this way, the

storagehierarchy is constructedfor each different need. _ •

All of the-_6rfirfiu_catlon hence-n-t_e v_ous_tasks is very standard client server

protocol, make a request, receive a reply; it makes use of the system very simple, as well as

modification and administration of the system--very, very simple. (Change of

vlewgraph} :

MR. R_ERMAN: This is the simphcity of the storage Option view from the bitfile.

The bitflle doesn't see much more than that.

However, below this point, we have analyzed and organized all of the information

that we believe we need to know. The head of development doesn't like me to say "all" about

anything; he's very sensitive about that, but I believe it's all of it that we need to know, and

it works!

We have broken this down to fixed and removable media. Disk is obviously fixed,

with a one-to-one media/device relationship. Most of the removable media that we are

dealing with, on the systems that we support today, use 3480 tape interface. Obviously, a

3480 cartridge tape is a one-to-one; however, the implementations of both helical scan and

optical disk have multiple logical 3480 volumes on each physical volume.

The reason for this analysis and breakdown is to make it simple, to be able to both

move data and make requests of the system, such as change devices in and out. We are not

aware of any devices that we cannot put into this organization, and with it. we will make

the subject of managing them very. very simple.

Now let me try and give you an example of what we have been able to do with this

approach. ....

" , ?:

(Change of viewgraph)

MR. RUDERMAN: If we take a iook at a particular system, let's say this system has

these options available to it. This includes the disks, helical tape, optical tape, and

standard cartridge tape.

A particular bitfile in the system may have attributes such that it can reside on disk

or helical tape or optical tape--it doesn't matter. If there is an image sitting on disk at a

point in time and this disk reaches its threshold and an event is t_ered Such that it needs

to be migrated or "scrubbed," as we call it, the option is: Do I put it here on helical tape or do

I put it here on optical disk?

We have built the system and designed the system in such a way that, as we can get

more information feedback from the hardware system, we can make that selection much

more sophisticated. What I'm driving at here is that the system manager may have said:

Because helical is faster, the next best choice for this file, when you migrate from the disk is

to go to helical tape.

If at a particular moment in time the helical system has large cues and is

overloaded, from a performance point of view, if the optical tape were available, it might

make more sense at that point in time to go there.

The kind of info_ation _qulred to be able to make those selections automatically,

transparent obviously to the user and transparent to the bitfile, will require some

additional information that tends not to be available today from most robotic suppliers.

And tfiat gets us into the challenge that we see in dealing with robotic storage

devices, and we have dealt with quite a few of them. When there are multiple and/or shared

robotic systems in a single archive, there are some potential problems that we think most

2-58
of the robotic manufacturers have not anticipated.They tend to think they are the only

deviceson the systemand they havenot anticipatedthe needfor programmaticdialogue

abouttheir own status.

But I believe that you win flnd that the user community is going to demand multiple

heterogeneous storage systems to be installed, and the ability to install and remove and add

and change any device at any time without taking down the archive demands the approach

we have taken.

So, what we have found is that the ability to do reads and writes is easy;, anybody

can do that. But the lack of a standard programmatic interface between software archive

systems and the storage devices is a problem. The one that we have implemented, and we

are pushing to become IEEE standard is the standard client server protocol. It's the same as

the ISO managed object interface for networks. It's the same protocol we use internally

between all of our task communications.

(Change of viewgraph}

MR. RUDERMAN: This is something we have all seen in any client server

relationship. With a storage server in this case, the client would make a request to the

server, and get a reply and/or be triggered wlth an event. {Change of vlewgraph)

MR. RUDERMAN: For instance, if an automated media library is shared, then how

do we know if a package we need is not being used elsewhere or has been ejected from the

device?

Because we are dealing with high performance requirements and massive amounts

of data, we would like to know that before we issue a read or a write so that we don't hang up

the archive system. The objective is to improve performance, not issue commands to any

device when a piece of media or the device itself is not available.

This is what we are looking to see. We have a design for it; we have implemented it

with certain devices, and others of you in the vendor world need to think about how you are

going to coexist in this environment.

(Change of viewgraph)

MR. RUDERMAN: Just summarizing. The devices currently supported, that we have

experience with, the 3480 cartridge, the STK silo, the Memorex tape library, Dataware

optical disk, and Masstor helical scan tape.

We see in the future adding additional archival devices. We are very interested in

lots of the new devices, in D-1 and D-2 areas especially. We also will be expanding network

connectivity to new standards, as they emerge.

We intend to be very oriented towards standards. Additional operating system

support is probably one that a few of you might be interested in. For those who don't know,

right now we are MVS-based. We definitely have plans for expanding beyond MVS to Unix.

A fundamental objective must be that all changes need to be transparent to the client

systems.

(Change of viewgraph)

MR. RUDERMAN: When we talk about adding new operating system support, what

we are really saying is that we don't see the world of data archiving suddenly and totally

abandoning MVS for Unix. MVS systems are very, very powerful for moving massive

amounts of data, simultaneously.

2-59
We seethe next version of our softwareto be able to have multiple distributed

servers,both for bitffle serving and for storageserversand multiple processorhosting.

including both MVSand Unix.

That's what we wanted to communicate with you today, and I'll think we'll make it

to lunch. You may ask some questions ff you'd like.

DR. FREESE: Thank you, Michael.

(Applause)

DR. FREESE: Questions. comments, discussion from the floor?

MR. SAVAGE: I do have one question. (Inaudible)

paraphrase that?

DR. FREESE: Could you

MR. RUDERMANi Yes, The questi0n had to do wRh, I believe, an interpretation of

the NCAR system, which was that the archive manager was really Just directing the

requesting system or telling it where the data was, as opposed to actually shipping it to it.

Yes. what you are referring to is the fact that there is direct data transfer between the

IBM disks and the Cray at NCAR. This is done for performance reasons, so the data does not

have to be sent through the IBM mainframe.

MR` SAVAGE: The IBM machine would look it up, find out what disk it was, and

ship that information to the Cray. The Ci-ay would then create a channel program and send

it down over that channel to actually directly read the disk.

DR. FREESE: Any other questions or comments?

2-60
Data Archiving.

Michael Ruderman

Mesa Archival Systems, Inc.

f

Computing Environment

USER

2-61
f

NATIONAL CENTER FOR ATMOSPHERIC RESEARCH

(NCAR)

Atmospherlc and oceanographlc research

Inititiator of IEEE Storage Model

Status

• Operational since 1986

• 2,000 users

• 102,000 3480 cartridges 5/91

• ~19 TB, growing at 6 TB/year with Y/MP

Imll. kit.

f

User Needs

• Data Integrity

Consistent, familiar Interface

No system dependencies

Accessable from everywhere

• Reduced local storage mgmt

,,g.S_,3._ _ ..,/

2-62

=

J

i

.=
\

System Manager Needs

• Data Integrity

• Storage hierarchy

• Mass storage alternatives

• Ability to deal with change

• Accountability by user

• Performance

• Reduced operations cost

Client System files

Users

I

MESA j

AclYn# _rxtm_=, kr..

2-63
f

Data Library System

• Central Archival Data Management Facility

• Standard Commercial Product

• High Performance Computer

• Access from Multiple CPUs

• Expandable, Device Independent Architecture

• Standard Operating System

• Standard Network Software

MeSA J AcNv _ ._,aems, In=

f

System Environment

• MVS/XA

• One dynamic user SVC

• SMP/E Installation

• Security software Interface

• Tape management system interface

264
f

Data Library System

_'_,.._!_

_:.__

i PHYSICAL

I VOLUME :

REPOSITORY

i

I STORAGE SYSTEM

SERVERS • __ADMINISTRATION

I ARCHIVAL OBJECT DATA BASE

DATA LIBRARY ACCESS MANAGER

I NETWORK ACCESS SERVER

I

NETWORK

DLS Environment

THE

DATA

LIBRARY

I

HEUCAL SCAN

St_aoe [_ CARTRIDOE TAPE

NETWORK I

THE

USER

COMPUTER

Storage

2-65
f

Data Library System

Network Access Servers

• FTP or User Access

• Unix File System appearance

• Gateway to DLS

Archival Object Data Base (AODB)

• Powerful Facilltlse

• Object Orientation

Storage Servers

• Uniquely Mounted Media

• Variably Mounted Media

System Administration

MESA j

Achk # _em_ k¢

f

DLS Features

• Modular Implementation

• Client applications

(Volume backup)

• Resource accounting

• Security

(Client - POSIX, System - MVS)

2-66
Networks

Protocols

• FTP, User Access

• TCP/IP, NETEX

Networks

• Ethernet

• Ultranet

• HYPERchannel

MESA j

AecNve/ _ k_

OS! Model

7 Application

6 Prmntatlon

6 Se_lon

4 Traneporl

3 Network [

2 Data Link

1 Physical

Ulllr

Acceu

NETEX

HYPERchanml

NETEX DRIVER

HYPERchannol

N_work

Acc_a

Server

Tranemimdon Control I Protocol

I Inlgr_ot proto_ I

I NolworkOrlver J

I Ethornet

Protoco4

Engine

Driver

Media Engine

Media

2-67
f

IEEE Mass Storage Reference Model

\

\

CLIENT

APPLICATION

SYSTEM

• Deals with Named Files - "Bitfiles"

• File Structure Insensitive

2-68
DLS and UNIX

• File Naming Conventions

• Directory Structure

• Command Syntax

• Security

m._, k¢

Client System Examples

• APOLLO AEGIS

• CDC NOS, NOS/BE, NOSNE

• CRAY COS, UNICOS

• DEC VMS, MICRO VMS, ULTRIX

• IBM MVS, VM, AIX

• PRIME PRIMOS

• SUN UNIX BSD 4.3

• UNISYS OS/1100

.,gs{_,=

2-69
The Users View

•User Capabilities

•Directory Organization

•File Security

f

User Capabilities

•Store a file

•Retrieve a file

Examine the directow

Other

2-70 @
Client System Commands

FTP Interface

• GET

• PUT

• DIR

• LS

• RENAME

Other

• USER ACCESS

• IMPORTEXPORT

MESA J

Act_ # _lwam& W¢

Other User Capabilities

• Add Adds a DLS directory

• Delete o,,°,,, a DLS file or directory

• Copy Creates e copy of s OLSfilewlthlnthe OLS

• Help Invokes DLS help facility

2-71
f

Ways to Organize User Files

•Simple (flat)

•Hierarchical (tree-structured)

f

Security

• DLS User Validation Password

• Owner, Group, World read / write access

• File read / write Password

• Account group, security & accounting

2-72
Multiple Mass Storage Devices

Differing User Storage Needs

Access Speed

Permanent Retention

Cost/MB

Interchangseblllty

Contlnulng Product Evolutlon

3480' 3490

New Mass Storage Devices

D1/D2

Optlcal tape

Archive / Storage System

archive system storage system

r_ FRAGMENT _._

FRAGMENT["

FRAGM ENT

2-73
f

Constructed Hierarchy

• Multiple views

• Dynamic

• Vary by bitfile or user

MESA j

/bchlv# _/stem=, _c.

bitfile

attributes %____

Image

storage options disk helical optical taps

P

=

2-74
f

Robotic Challenge

• Multiple / shared robotic systems

• 3480 service Interface not sufficient

• No standard programmatic interface

Client / server protocol recommended

(ISO managed object)

MESA j

package Injected - in the robot

Injectable - out of the robot

surface mounted - In a drive

mountable - out of a drive

media opened - has an active file

openable - has no active file

MESA J

Achl_ wl5bl_em=. Ire

2-75
i

Archival Devices

• IBM 3480/90 Cartridge Tape

• STK 4400 Cartridge Tape Robot

• MTC 5400 Automated Tape Library

• DataWare Optical Disk

• Masstor Helical Scan Tape

MESA j

AciWd 5_rlam_ k¢.

f

System Implications

Media Orientation

Media/Device Relationships

Robot Awareness

User Profiles

MESA j

2-76
f

Vendor Implications

Storage Management System

• Must be unbound from File System

• Bitflle "instances"

• Must be aware of different media, devices, robots

Robotic Systems

• Must be able to Interact with SMS

• Media content and status

• Must notify "clients" of changes

• Emerging ISO standard for managed objects

MESA j

IVchkd _Rm_, Ire.

DLS /IEEE Storage Model

Active committee member

General compliance

Organization of physical volume repository

• Media sets and pools

Multiple archival devices

Direct I/0 capability

Commitment to continued compliance

2-77
f

System Growth

• Additional Archival Devices

• Additional Connectivity Products

• Additional Operating System Support

• Transparent to Client System

Future Direction

Verslon 3

• MVSorUnlx

• Multiple processor hosting

• Support for Version 2 PVR

_,_sA j

Wuel. k¢

2-78
User Factors

\

• Prevalence of Unix

• Mass storage devices

• Software and people expense

•. Integrity and performance

• Standard network support

MeSAj

.4¢/Wa'Sy=ams=. kin.

MVS

System integrity/availability

Proven I/0 throughput

Wide range of I/0 devices

Security

UNIX _

Standard, familiar interfaces

Standard development platform

Standard networks

.M_SAj SyWm, t¢ km

2-79
f

f

Implementation Factors

k

Multiple flavors of Unix

:r

Mass storage driver Support

• Unix vendor commitment to performance

• Relationship with Unixvendor

Benefits

Client System :

• Reduced disk end tape drive expenditures

• Reduced operational expense

• Reduced media expense

2-80
Benefits

• Improved data Integrity

• Higher rate of data backup

• Increased data reliability

• Control of organizational data

• Ability tO dell wlth change

n

MESA j

Act_d _blNeml k¢.

f

Implementing the DLS

•Hardware Configuration Planning

•System Customization

•Installation Planning

•Training and Support

2-81
DLS is a Central Archival

Data Management Facility

• I/0 Server Computer - MVS

• Standardized Library Access from Multiple CPUs

• Standard High Speed Networks

• Expandable Device Independent Architecture

MESA

Ac/dvd 9j,_em=, tnr..

i

Archiving Facilities

• User / system initiated transfers

• Simpleuser interface

• Archival device Independence

,#,{s_,.=j

2-82
f

Backup Facilities

• List-driven backup

• Media clustering by expiration date

• VAX / Unix backup utility

f

Mesa Archival Provides ,..

• Data Archival Product

• Data Archiving Expertise

• Archival System Integration Capability

2-83
\

Fmmzm
N93-16326

NETWORK ACCESSIBLE

MULTI-TERABYTE ARCHIV

NSSDC CONFERENCE

GODDARD SPACE FLIGHT CENTER

JULY 24, 1991

Fred Rybczynski

Metrum Information Storage

2-85 PRECEDING P,_GE o, ^,,,,," •.,--_',_ NOT F!LMED
Metrum

ROTARY STORAGE

(RSS)

SYSTEM

T-120 Super-VHS media with 10.4 GB per cartridge

Very Large Data Store (VLDS) tape drives

- Sustained 1.0 MB/S with Read-After-Write

-- 1E-13 Bit Error Rate w/error mgt software

- 45 sec average file access time

Robots with on-line capacity to 6.2 TB

Bar code reader

Data management computer

Data referenced by file name

Files organized by hierarchical directories

File and directory access protections

Network accessible

Me_unl

METRUM INFORMATION STORAGE

SYSTEMS BASED ON STANDARDS

MEDIA

• World-wide VHS media standard

• T-120 half-inch tape cartridge

• Billions of cartridges sold

TAPE DRIVE

• SMPTE format VHS transport

• Millions of transports sold

• Commercial grade

ROBOT

• Commercial broadcast industry

....... _2-86 .:-
METRUM INFORMATION STORAGE

STANDARDS - concluded

BAR CODE READER

• Standard formats

INTELLI GENT DATA MANAGER (COM PUTER)

• UNIX based

• POSIX compliance

NE'I'WORK CONNECTIVITY

• Ethernet TCP/IP and DECNET

• HYPERCHANNEL

• FDDI

• GOSIP

• NFS

Me, urn

Inf_mm balll

MANAGED DATA STORAGE

GOALS

Maximize data per unit volume, balanced by

Cost/MB of Media

Cost/MB of Technology

Required data rates

Optimize media access

Unattended media access

Media ID verification

Speed of loading

Provide ease of access to the data

Easily identify data to be stored/retrieved

Concurrent access from multiple computer systems

Me_'um

i_imm dm alo._

_llwt .i,)

2-87
Metrurn

bfw m_ l_

[1t olgo _)

STORAGE HIERARCHY

TYPICAL MEDIA PRICE/MB

\

Price/MB

$1000.00

$10.00

$o.15

$ O.Ol

$ o.oo3

$ 0.05

Met:rum

[I _OtIO-IkJ

STORAGE HIERARCHY

TYPICAL ACCESS TIMES

Access Time

1 micro sec

15 msec

250 msec

10+ sec

< 60 sec

min to hrs

2-88

=

i

r

eL=

W:
VOLUME COMPARISON

6 Terabytes

6

q , ID

52'

9-Track, 6250 bpi

2400 It, 170 MB

35,000+ Reels

850+ Sq Ft

P 57,'

T-120 Cartridge

10.4 GB/Cartridge

600 Cartridges

4SqFt

Metrum

F_,Oltl =_1

VOLUME COMPARISON

One T-120 Cartridge (10.4 GB) Equals

• 61 nine-track reels at 2400 ft/reel,

6250 bpi and 170 MB/reel

• 50 cartridges of 3480 at 200 MB/cartridge

One Cubic Foot of Storage Can Contain

• 12-15 nine-track reels

• 60 cartridges of 3480

• 30 T-120cartridges

(equals 70 nine-track reels)

(equals 1,800 nine-track reels)

M_um

2-89
Metrum

RSS FEATURES

• 6.2TBin<20sqft

• System cost < 8.5 cents per MB

(RSS-600, 2 drives, 600 cartridges = $530,000)

• Media cost < 0.3 cents per MB

($30/cleaned and certified cartridge)

• Unattended operation

• Network accessibility

• Read-After-Write reliability (1E-13 BER)

i

Me'_'ucn

I

_,I, _I

RSS DATA ACCESS

• Archive system accessed via network

• Access authorization screening (UserlD & Password)

• Entire archive looks like a single huge disk

Data accessed by file name

- Multi-level hierarchical directories

- Selective directory & file protection

• File access is random (cartridge rewind not required)

• Avg file access is 45 sec for loaded cartridge

• Cartridge load in < 8 seconds

• Intelligent queue management

2-90
RSS DATA MANAGEMENT

Database Management System

- 90 million files

- 65,000 cartridges

- Maintains system performance log

- Comprehensive report generator

Monitors system events

- Errors are categorized by severity

- Multiple notification targets, including e-mail

- Incorporates recovery algorithms

User data can be directed to specific cartridge(s)

Admin functions available at console & via network

_um

m

RSS ADMINISTRATION

MENU MAP

I BASE MENU 1

DELETE FOR

FULLPATH

t

I "o_oMEs J

,.

,_uA_sT_ UPDATE

DELETE

COMPRESS

FORMAT

STATUS

I

I

[ _acHIvEJ

STATUS

FULL BACKUP

PARTIAL BACKUP

Me1_um

_mdm_ llwqe

2-91
Metrum

m_m41m lyreall4

_U31691_r}

M_l.lm

RSS ADMINISTRATION

BASE MENU

AMASS Administretio_

Version: AMASS/2.4

File_(1) Volumes(2) Drivee(3) Archive(4) System(b')

Wipe(0) Nelp(PF2) End(PF3) Q_t(PF4)>:

RSS ADMINISTRATION

FORMS INTERFACE

FILES/ RETRIEVE MENU

AMASS Administration

Name: _9g0_wp.. file_

User: 100 Record: 32

Group: 101 Parent's Record 15

Mode: rwx .... Volume:

Type: Oirecton/ Vo(ume Grm,_: 3

Size: Starting Block:

Atchived: 01-13-_)1 13:18:22 Bad Blocks:

Accessed: 01.13.gi 13:18:2"2 N," of Erron=:

_. 3 of 13

Files/_et rieve

Update Delete Futlpeth

2-92
RSS HARDWARE ARCHITECTURE

Me'o'um

_m_ 5_a41e

SUN

PROCESSOR

16 MB

MEMORY

CIPRICO

SCSI HBA

SUN SCSI &

ETHERNET

CONTROLLER

ESDI DISK

CONTROLLER

CONSOLE

DEVICE

R8-232

SCSI

$C81

__1_____

QIC -24

CARTRIDGE

TAPE

ROBOT

i VLDS ]

_VLDS l

RSS SOFTWARE ARCHITECTURE

ETHERN ET TCP/I P NETWORK INTERFACE

T ' ET,

i_ _-1_o._q! su.o_V,.TUA. R.E.Y.TE_

'"Ul/, _,,F-I IIF | _[ TAPE LIBRARY VIRTUAL FILE SYSTEM J

R-EGTIONAL DATABASE MGR / TAPE DRIVE

DISK i 'NTERFACE

_ _ CACHE I

CARTRIDGE

DATABASE LIBRARY

Metrum

m

2-93
RSS SUPPORTS MULTIPLE

CONCURRENT PROTOCOLS

RSS SERVICES

ARCHIVE

ADMIN

FUNCTIONS

SUNOS VIRTUAL FILE SYSTEM

TAPE LIBRARY VIRTUAl. FILE SYSTEM 1

MO{)'Uk'l"m

i l I I

• TCPylP" "DECNET" "OSI"

APPLICATION

PRESENTATION

SESSION

I"P, ANSP@RT

NE'P, NORK

APPLICATION APPLICATION

PRESENTAltQN PRESENTATION

SESSION SESSION

TRANSPORT TRANSPORT

NETWORK NETWORK

DATA LINK

...... PHYSICAL

f

ETHERNET

APPUCATION

PRESENTATION

SESSION

")3:;[ANS PORT

NETWORK

DATA UNK

PHYSICAL i:

f

HYPERCHANNEL

Metrum

m m

DATA SOURCES

• Data acquisition systems

• Data transcription systems

• Local computer file systems

• Remote computer file systems

t

_ ,__.,,!,m ul ._.... m,) =mu)

RSS-600

ARCHIVE

LIBRARY

2-94
TAPE DRIVE CONFIGURATIONS

READ-AFTER-WRITE VLDS

• 1 MB/S fixed rate, read while write

• 1E-13 BER with error management software

• 10.4 GB cartridge capacity ($.002/MB media cost)

• 6.2 TB in RSS-600 ($.085/MB system cost)

TAPE DRIVE CONFIGURATIONS

VLDS FAMILY

• 1 - 4 MB/S fixed rate

• 1E-8 to 1E-10 BER, config dependent

• Variety of interfaces

• Up to 10.4 GB per cartridge ($o003/MB media cost)

• Up to 6.2 TB in RSS-600 ($.085/MB system cost)

Metrum

tr,4w__ m_ Nl u!.'-- ' ,- ,'!u_ In I

2-95
TAPE _DRIVE CONFIGURATIONS

BUFFERED VLDS

Mo_a-urrl

i,,_q,,m,q=,_,

Mol_t.lm

lo'rag_ -_l

• 0- 4 MB/S variable rate

• 4 MB/S maximum sustained rate

• 20 MB/S burst (16 MB buffer)

• Variety of interfaces

• 1E-8 Bit Error Rate

• 10.4 GB cartridge capacity

• 6.2 TB RSS-600 capacity

($.003/MB media cost)

($.09/MB system cost)

TAPE DRIVE CONFIGURATIONS

RSP-2150

• 0 - 2 MB/S variable rate

• 2 MB/S maximum sustained rate

• 4 MB/S burst rate (8 MB buffer)

• SCSI or PERTEC interface

1E-14 bit error rate (auto re-read/write)

Up to 14.5 GB per cartridge ($.001/MB media cost)

• Up to 8.7 TB in RSS-600 ($.06/MB system cost)

...... :: -2-96
OPTICAL TAPE

HD-1000

DRIVE

• 0 - 3 MB/S variable (3 MB/S sustained)

• SCSI interface

• 1E-12 bit error rate (auto re-read/write)

• 1 TB per reel ($.005/MB media cost)

• 28 sec avg access time (60 sec end-to-end)

• $250K drive cost

• Future adaptation to RSS-600 chassis

_klb'uff_

p'is, lpl._l

RSS ARCHIVE ARCHITECTURE

SUMMARY

• UNiX-based operating system

• Standard network protocols

• User-directed archiving

• Supports automatic archiving

• Managed data

• Fast, easy accesS

1_IOII'L,_tl

_q,m,d_ u_tqm

2-97
@ ICI Imagedata N93- 16327. ,

ICI Optical Data Storage Tape

Robert .4 McLean

Joseph F Duffy

1. Introduction to flexible optical media

Optical data storage tape is now a commercial reality. The world's first successful

development of a digital optical tape system is complete. This is based on the Creo

1003 optical tape recorder with ICI 1012 write-once optical tape media.

In order to understand the significance and potential of this step change in recording

technology, it is useful to review the historical progress of optical storage. This has

been slow to encroach on magnetic storage, and has not made any serious dent on the

world's mountains of paper and microfilm. There are numerous reasons for this, the

most of important of which are:

The long time needed for applications developers, systems integrators and end

users to take advantage of the potential storage capacity.

Access time and data transfer rate have traditionally been too slow for highperformance applications.

• Optical disk media has been expensive compared with the competition, eg

magnetic tape.

As one of the world's major international chemical companies, ICI's strategy in response

to these concerns has been to concentrate its efforts on flexible optical media; in

particular optical tape.

2-98
@o

ICI Imagedata

Manufacturing achievements

Flexible optical media offers many benefits in terms of manufacture; for a given capital

investment, continuous, web-coating techniques produce more square meters of media

than batch coating. The coated layers consist of a backcoat on the non-active side; on

the active side there is a subbing layer, then reflector, dye/polymer and transparent

protective overcoat. All these layers have been tailored for ease of manufacture, and

specific functional characteristics.

3. Media characteristics

The media has the ability to deliver high system performance and functionality over a

very wide range of system capacities, depending on the drive design and media format.

In addition to low cost per MegaByte, this can also be achieved with the archivability

and indelibility that is vital for many storage applications. Consequently, the media

permits the development of drives and systems that provide a unique set of features:

• Low on-line cost/MB: 10¢ to 40¢/MB depending on the format.

, Low media cost/MB: _¢ to I¢/MB at first, falling with time.

High performance in access time: the low track spacing and high longitudinal

speed of fixed head optical tape drives allows search rates between 2 GB/s and

20 GB/s. This compares very favorably with helical scan magnetic drives.

High data rate: a single laser channel can achieve 4 MB/s with 60 mW on the

media surface, and this can readily be increased with the use of multiple lasers.

High volumetric efficiency'." flexible optical media offers efficiencies a factor of

10 higher than advanced helical magnetic recording.

Indelible media: the original information cannot be erased and altered.

2-99
ICI imagedata

Unlimited read cycles: non-contact recording means that the data will survive in

excess of 30,000,000 read cycles. The number of tape wind cycles is very high.

Long media lifetime: the use of chemically stable materials has allowed us to

predict a lifetime in excess of 15 years.

4. Media lifetime

Optical media based on organic, dye/polymer materials is well-known for its chemical

stability. An unfortunate consequence of this is the difficulty in predicting a lifetime.

Several accelerated aging techniques are in :common usage: steady-state elevated

temperature and humidity with Arrhenius extrapolation; elevated levels of temperature

plus corrosive gases (the "Battelle" test); and chemical stability investigations.

We have used all of these extensively, both to attempt to predict an absolute lifetime

limit, and in comparisons with magnetic tapes: iron oxide, cobalt modified iron oxide,

chromium dioxide and metal particle formulations. We have also compared our media

with rigid optical disks, including stability to uv light.

The Arrhenius test is performed at various constant conditions of elevated temperature

and humidity (Ref. 1). The test assumes the following relationship, where failure is

dominated by one chemical process with a given activation energy: 1/time=A{eEAr}.

We defined failure as a change in reflectivity (Fig. 2) or a drop-off in the Carrier-toNoise Ratio (CNR) (Fig. 3). In fact, within the measurement accuracy, failure was not

detected for any of the samples, and this test is continuing. A better way of detecting

failure is to measure the raw BER on a drive; we are now doing this on the Creo

drive. However, by assuming that failure did occur, it is possible to estimate a lower

..... ilimit on the lifetime (Fig. 1). The mildest conditions of 55 °C and 60 %RH do not

correlate with a straight line through the three data points at more severe conditions.

The slope of the graph gives an activation energy of 1.12 eV. A comparison with other

forms of optical media is shown in Table 1.

2-100
ICI Imagedata

This implies that in comparison with the sample that failed after 121 days at 75 oC and

60 %RH, a sample kept at conditions of 20 *C and 60 %RH would survive for an extra

393 years!

We have used two standard uv stability tests. The British Standard Blue Wool Test was

developed for dyes used in the clothing industry. It assesses light fastness on a scale

of 1 (low) to 6 (high). ICI's data storage dye measures > 4 with the test still

continuing. By comparison, the average textile dye measures < 4.

The British Standard Accelerated Weathering Test exposes a sample to 120 hours under

UVA light at 55 *C and 60 %RH. This is equivalent to 72 hours of sunshine. Under

this test we saw 1% drop in reflectivity. These results are similar to that for Sony

Century Media in an identical test.

We also compared our media to metal particle and metal oxide tapes. In the case of

metal particle, we compared changes in recording characteristics, and for metal oxide,

we compared the chemical stability.

The metal powder tapes were stored under accelerated aging conditions, and the

recording characteristics were assessed by looking for any changes in the magnetic

properties. We bought two tapes; tape "A" is consumer R-DAT and tape "B" is 8 mm

video, and both were different major Japanese brands.

The test method consisted of storing the tapes at a constant 60 *C and 80 %RH for

3 and 6 weeks, plus keeping a Control tape at room conditions. The magnetic

properties were then measured in a high saturation field VSM. This work was clone

under contract for ICI by the Fulmer Research Company in the United Kingdom, and

is summarized in Table 2. This shows drops in signal strength of up to 22% after 6

weeks.

We performed an analogous test on the ICI optical tape out to 9 weeks (Fig. 4). The

signal strength was unchanged, and the CNR curves, did not change within the

2-101
ICI Imagedata

measurement accuracy. In addition, we used a Time Interval Analyzer (TIA) to look

for an increase in the intrinsic error rate by measuring a Geometric Error Rate (GER)

on unwritten media, and looking for changes. The GER is directly proportional to the

sum of the defective areas. Figure 5 displays this against the detector threshold level,

normalized tO unwritten media at 100%. Poinis below 100% are Clark defects, and

those above are light defects.

ICI media darkens upon writing and a typical detector threshold level is 60%, so the

GER appears to have increased by less than a factor of 2.

Temperature cycling tests can be used to test not only the chemical stability of the

media, but also the mechanical integrity of the structure. It is not possible to estimate

a lifetime from cycling tests. We subjected the optical tape media to 20 temperature

cycles defined by Fig. 6. We again looked for changes in the recording characteristics.

There was a 1 or 2 dB drop in the CNR (Fig. 7), which is just greater than the

measurement accuracy. The time interval results presented in Fig. 8 showed a

corresponding increase in the signal jitter (standard deviation) by 3 ns. The "(+/-)"

refers to triggeririg on therising and falling slopes of the signal, and "(-/+)" is the other

haif cycli_i _

A range of oxide magnetic tapes were stored under accelerated aging conditions, and

any degradation was assessed by looking for any decomposition products, This work

was also done under contract for ICI by the Fulmer Research Company in the United

Kingdom.

We tested three tapes; tape "C" is iron oxide instrumentation tape, tape "D" is cobalt

modified iron oxide mS consumer video tape, and tape "E" is chromium dioxide IBM

3480 type data cartridge tape.

The test method was to store the tapes at a constant 60 *C and 80 %RH for 3 and

6 weekS, while keeping' a Contr01 tape at room conditions. Then standard solvent

extraction techniques were used to look for any decomposition products. One meter

2-102
ICI Imagedata

length samples were immersed for two hours in a Soxhlet extraction by Delifrene, then

the soluble extract was weighed. This was followed similarly by a further two hours in

acetone, then weighing the extract.

The results are presented in Table 3. The initial extract is a baseline, and the

percentage increase above this is a measure of chemical decomposition in the binders.

These results can be put into perspective through a paper by Bertram and Cuddihy (ref.

2). This states that after aging, an increase in extract of 1.4 % by weight corresponds

with a degradation in tape performance. When our results are compared with Bertram

and Cuddihy's, there was very good agreement for the Tape "C".

We performed a similar chemical stability test on the optical tape. Again, the test

method was to store constant 60 oC and 80 %RH, plus 80 oC and 80 %RH for 1, 2

and 3 weeks, plus a Control tape at room conditions. We were unable to detect any

decomposition products at a constant 60 °C and 80 %RH, and so the test was repeated

at the more severe conditions of 80 oC and 80 %RH for three weeks.

We devised an extraction technique suitable to the solubility of the dye/polymer

material. This involved immersing 500 cmz samples for 72 hours in a Soxhlet extraction

by ethanol. Samples and extract were then weighed and analyzed by sensitive FTIR

techniques. Using FTIR, we could detect binder degradation only at the harsher

conditions of 80 *C and 80 %RH, for a minor component of the protective overcoat,

not the recording layer. The quantities were too small to be weighed.

Another test we used is the Battelle Class II accelerated aging test, performed under

contract at the Battelle Institute in Ohio. This test has been correlated to aging of

materials in cities and other locations where combustion byproducts form a mix of

corrosive gasses. A fully assembled open reel ICI 1012 Optical Tape, without the

protective sealed storage and shipping box, was kept at a constant 23 °C and 70 %RH

in a flowing mixed gas environment consisting of 10 ppb HzS, 10 ppb Clz and 200 ppb

NOz for 30 days. This environment has been correlated to 15 years lifetime. We

detected no damage in terms of corrosion, reflectivity or modulus.

2-103
@.

ICI lmagedata

Conclusion

Optical tape systems can offer a unique set of attributes to potential end-users. The

use of chemically stable recording materials, indelible write-once technology, plus the

advantages of non-contact reading and writing, yield a very robust and archiva!medium.

Our lifetime studies have concentrated on measurement techniques and comparisons

with magnetic technologies that are independent "of the drive and read/write channel.

The comparisons with magnetic tape technologies are favorable:

No deterioration in optical recording characteristics after 9 weeks at 60 *C and

80 %RH.

Metal particle magnetic formats show up to 20 % deterioration in magnetic

capability after only 6 weeks.

No binder hydrolysis in the recording layer after severe environmental exposure

and extraction process.

Minor hydrolysis present in overcoat after 3 weeks at the extreme conditions of

80 °C and 80 %RH.

Clear evidence of deterioration in magnetic oxide tapes under an industry

standard test.

We plan to extend these studies to raise the lifetime prediction for ICI 1012 optical

tape from 15 to 30 years, and to characterize any changes in the raw BER through the

readAvrite channel on the Creo 1003 optical tape recorder.

References

,

.

A B Marchant, Optical recording: a technical overview, Addison-Wesley Publishing

Company, pp 380-382, 1990.

H N Bertram and E F Cuddihy, "Kinetics of the Humid Aging of Magnetic

Recording Tape", IEEE Trans Magn, vol MAG-18, no 5, pp 993-999, Sept 1982.

2-104

i

B

E

E

_B
ICI lmagedata

Table 1

r

Company Media Type Test Method Activation

Energy in eV

i ,' u

Sony Metal Alloy BER 1.5

ICI Dye/polymer %R and CNR 1.12+

OITDA* Multi WORM %R I. 0

Hitachi

NEC

12" WORM

Magneto-optic

BER

DER

1.0

0.97

*OITDA = Japanese Standard Committee for the Optical Data Disk

Table 2

Tape

IIAI!

,IBTape

Time

Control

3 weeks

6 weeks

Control

3 weeks

6 weeks

Time

M. % fall

3 weeks

r ,, •

i0.64

18.84

0

4.20

22.35

M r % fall

0

11.30

20.34

0

4.38

22.31

Table 3

Total Extract

in %

Sq % fall

0

0.74

1.84

1.45

0

0.19

-0.015

Increase in %

Control i. 20 0

"C" 3 weeks 2.35 1.15

6 weeks 3.49 2.29

Control I. 24 0

"m" 0.21

6 weeks 1.86 0.62

' i" "

Control 1.53 0

"E" 3 weeks 2.04 0.51

6 weeks 2.55 1.02

2-105
ICi imagedata

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¢

o -16

n

d

s -16.5

-17

2.6

Asrhenius Relationship

ICI 1012 Optical Tape: Steady Stale EnvtronmentaJ Test

60 _ at different temperatures

\

Activation

1

\.

\\

\

\\

\

\

2.7 2.8 2.9

1CXX)/Temperalure "C

Energy = 1.1_ eV

3.1

• 55 "C (160 days)

• 75"(:; (121 days)

• 85 "C (53 days)

[] 9s"c (19days)

R 45

e

f 40

I

• 35

c 30

t

i 25

"4

i 20

t

15

Y

10

i

n 5

% 0

_tiv_ Time

ICI 1012 Op_icaJ Tape: Steady Stale Environrnenta] Test

60 %RH al different temperatures

i-u llu-

• 55 "C (160 days)

• 75 "C (121 days)

• 85 "C (53 days)

E] 95 "C (19 days)

20 40 60 80 100 120 140

ol Expoeure

160

Rg. 2

2-106

/
ICI Imagedata

Fig.3

C

N

R

I0

0

0

CNR vs Write Power

ICI 1012 Optical Tape: Steady State 60 _:IH

3.75 MHz, 8.5 m/s, 50% duty cycle, 30 kHz bandwidth

| 1 I ..iJ

iib__--

6 8 10

Write Power in mW

/\

12 14 16

X Control

• 55-c (116days)

• 75 "C (121 days)

• 85-c (53days)

5O

4O

3O

2O

10

8 9 10

CNR ve Write Power

ICl 1012OpticalTape: Steady State 60 "C/80 %RH

3.75 MHz, 8.5 m/s, .50% duty cycle, 30 Id-lzbandwidth

___-,ir.... ,

11 12 13

Write Power in mW

14 15 16

Contro_

1121 Days

• 42D_,
ICI lmagedata F;g. 5

G

E

R 10

8

r 1

b

i

t

f

a

r 0,1

Y

0.01

Geometric Erro( Rale vs Threshold

ICI 1012 Optical Tape: Steady Stale 60 "C/80 %RH

L4-

I!|

: !-:

i i

4O 6O

Threshold (% o_unwritten)

X Control

1121

• 42 Days

63 Days

80 lOO 12o 140

Time

eralure Cycl

, !

T 6O

e

m 50

P 4O

e

r 30

a 20

t

u 10

r 0

e

-10

i

-20

n

-,3O

Temperalure w Time

ICI 1012 Ol_i_zJ Tape: Temloeralure Cycle Te_

Com_ant 8O %RH

II

ml

m

0 1 2 3

Time in Houm
ICI Imagedata

_.7

d

B

50

40

30

20

10

CNR vs Write Power

ICI 1012 Optk_al Tape: 20Temperature Cycles

4.4 MHz, 8.5 m/s, 50% duty cycle, 30 kHz bandwk:lth

I

I

8 9

! ..... I!-

10 11 12 13

W¢ite Power in mW

14 15 16

[] Before

• After

20O

175

T

i 150

m 125

e

i IO0

n 75

n 50

8

25

Time Interval Analys_ v_ Write Power

IC11012 Optk_al Tape: 20 Temperature Cycles

4.4 MHz, 8.5 m/s, _ duty cycle

1--..... 4

q

10 11

I

"-'"_ ...... t_ .... :__::::_

/

_1-...... It-- --il .... :-! F=-_

I,.-...... _ ..... _- ..... _. ..... __

12 13 14 15 18

Write Power in mW

[] (+/-) Mean - before

• (+/-) Mean -attef

Z_ (4+) Mean - before

• (4+) Mean- after

<_ (+/-) Jitte¢ - before

• (+/-) Jitt_ - after
N93- 16az8. 

Presentation for NSSDC Conference

Mass Storage Systems and Technologies

for Space and Earth Science Applications

ATL Products Division's Entries Into the i

Computer Mass Storage Marketplace

|

July 2_, 1991

"_'_,_..,'_A, '= ,_

I)C_'UM]_T NO. _1011CC_ A _L lmr_dU_taOdeWll_Rfi ©s i

@detics Background

• High Tech Company Founded in 1969, Publicly Traded

- ServingWell-DefinedNicheMarkets

- ThroughVarietyof ProductGroups

• Roots areoln Space Borne Recorders !

- Own 80_ of Marketplace

• Evolved Into Robotics in Mid-70s

- AIM, Broadcast,DMS, ATL ProductsDivisions

- 35% of RevenuesandGrowing

- Technologyand PeopleMove FromOne Divisionto Another

[

I_K)O.TIO[IE_F I'_. gO 110_ AFIL _ _

_v, ,,,, Odetics

2-110
Spaceborne Tape Recorder

NO. _ I0_ ATJL lnrodLm_ Imhddmt

,_Y.,_l Odetics

r

Product Evolution

_1 ,,

DOCIJMI_ NO. g011 _2

_ILy, 1_1

* Robotics Genesis - AIM

• Company's High Technology Group

- 1979 Committed to a Six Legged Robotic System

- 18 Months Later Demonstrated ODEX I

• Symbolofthe CorporateCommitmentto Robotics

- Demonstrates High Strength to Weight Ratios

- All Electric, Compact, Extremely High Performance

- Six Units Built - Three Generations of Technology

• Predominantlyfor NuclearPlantMaintenance

• Evolution to Other Robotic Subsystems

- Arms, Hands, and Effectors

ATI. Produeb _s/on

Odetics

2-111
Three Generations of ODEX

_ NO. gOll_

F_I..Y', ! g91

& T_ PV_dim_ I_lllm

Odetics

Product Evolution

Technologies and Markets Served

• Innovators in "Small Package" Handling

• Do Not Serve General Purpose Robotics Handling Market

• Design Intent of Our Products

- Move"Small Light WeightObjects."Very Quickly

- Accent On Longevity of "Object" Being Moved

- High Degree of Reliability

• Necessitates

- Expertise in Low Mass, Light Weight, HighSpeed Systems

- Requires Unique Robotic Handlers,Arms, End Effectors

- Products Designed for Niche Markets

• ApertureCardStorageModuleSystems

• TapeCassettesandCartridges

• OpticalDisks

IMX?UM][_ NO. 9011002-2

JULY, I_1 Odetics

2-112
Product Evolution

Infodetics' Aperture Storage Module Library

• First Linear Servo Based Expandable System

• Modules: 10 Ft. Long By 3 Ft. Deep By 7 Ft. High

- 2000 Cartridges Per Two Rows or Module

- 100 Aperture Cards Per Cartridge

- Robotic Handler in Aisle Between Rows Within Module

• Large System With Multip!e Modules and Pass-Through

• 5 Seconds Average "Pick and Place"

- Access Cartridge and Load Into Aperture Card Reader

• Document Management System "Storage Server"

- Cache Microfilm Images to Disk

- Transmitted to Work Stations for Viewing

DOC'Ulk4gD,_ NO. q)0110_ A1PL iWNduwb _ew

_v. 1,_ Odetics

Product Evolution

Broadcast Division's TCS2000 Video Cart

• First "Tower" Based Expandable System Introduced '86

- Designed as a TV Station or Network Automation System

• Built as Part of a Joint Venture With RCA in 18 Months

- RCA Dropped Out, Odetics Entered End User Market

• System Consists of:

- Robotics and Upto 6 Tape Recorders Per Tower

- 225 to 300 Tapes Per Tower Depending On Formats

- Switchers, Sequencers, Monitor and PC Based Work Station

- Hierarchical Software

• Real-TimeController/OperatingSystem,RelationalDB, Playlist

• Supports VHS, Beta, D-2 Formats

• Robust, Redundant and Extremely Reliable

DOCUMENT NO. 9011002

JULy. I_1

,J

AI'L Prn.du_ m_fe/e,n

Odetics

2-113
f

TCS2000 Cart Machine With Library Expansion Module

_ I,IO. _I011002 AIt'L/_ l_hdrs/al

_v, l_l Odetics

Broadcast Division's Newest Product

TCS90 Videocart System

* Bookshelf Design

- x-Y HighSpeed LinearServoSystem

- One ArmedGripperWith HoldingTray

• Accommodates Combination of Cassette Sizes and Format

- BetaSP, VHS, or D-2

- SmallandMediumSizes

• Tape Recorders are Standard: Non-Modified

• Autoloader Accommodates Up to 8 Cassettes

• Fixed Size

- NoExpansionCapabilities

• Software From TCS2000 Migrates Directly to This Product

50 ManYears of Development

DO_NT NO, 9011002

IULY, I_)1

Alf¢ I_u_lUCb IhMN,n

Odetics

r

O

2-114
.r ..,

TCS90 Cart Machine

ATL Products Division

Marketing Strategy

• Serve the Evolving Computer Based Mass Storage Market

• Develop Library Automation Subsystems

- Robotics, Control, Storage and Computer Interfaces

- Support a Broad Range of Tape Sizes and Formats

- Interface to a Variety of Tape Drives in Each Size

- Provide Low Level Library Control and Management Software

• Sell Through Distribution Channels That:

- Integrate Tape Drives

- Add High Level Mass Storage Management-Software

- Service a Broad Range of User Markets

- Provide "Private Labelled" and "General Purpose" Products

• Pursue Major Market Shares

- High Density/High Capacity Storage Market

- General Commercial Market By Supplying a Range of Solutions

IXX'IJMENT NO. _01100_-2

JULY, I_)|

J

AI_ Iq'cdLmtl ml4ldkm

Odetics

2-115
High Density Systems Business

Product Lines

• Developing Two Basic 19mm ATL Storage Subsystems

- To Serve High Capacity Markets: Terabytes and Petabytas

- Support Small arid Medium Size D-2 Cassettes

• Expandable "Tower" Based System

Broadcast System as Platform

- Auxiliary Towers for Expansion

Delivered March. 1991

• New Linear Aisle Based Expandable System

- 30 Months in Development: Delivery August, 1991

- Most Advanced Robotic System On the Market

19mm Aisle Based ATL

2-116
19mm ATL Cut Away

Side View of Robots

High Density Systems Business

Product Lines

• 10 Minute Video On Two Technologies

- Copiesof Video AvailableUponRequest

- Text of NarrationFollowsPresentation

DOCUMEN'r NO. 9011 {X]2.2

TOLy, I_1

./

AI"L I_*edue_ Dhd_

Odetics

2-117
E-Systems Business Relationship

• Exclusive Supplier of 19mm ATL Subsystems

- Computer Mass Storage Marketplace Only

• Can Market Other Odetics ATL Subsystems

• E-Systems is the Integrator

- Providing Systems Expertise - ATLs, Tape Drives, Computer Integration

- Library Management Software forthe ATLs

- Supplying Storage Server Software

IX)CUMENT NO. $OI1002

JULY, Iggl

J

AlfILl_'NIm_b_

Odetics

r

3480 "Medium Size" Library

First Commercial Product Offering

• "300" Cartridge Baseline System

- Expandable in Increments of Approximately 300 Cartridges

- "1500" Cartridge Maximum

• Up to 2 Tape Drives Available In Baseline

- Up to 4 Additional Drives as System Expands

- Supports All Low Cost 3480 Tape Drives

• Small Footprint

- Fits Standard 28 Inches Wide By 45 Inches Deep By 78 Inches High Cabinet

- Very High Density Storage

• Cartridge Autoloader and Bulk Loading

• RS-232C or SCSI-II Interface

• Serve the Distributed Computing and File Server Markets

IX)C_ML_c_ N(3 901 l_

/ULY. 1991

J

Alff. lq, edl_hl BNC_dkm

Odetics

2-118
Storage and Library Management

• ATLs are Driven With "Low Level" Commands

- Pick From Bin and Move to Tape Drive

- Status Provided Back Through Sensors

- Electrical Interface: RS-232C. Ethernet, SCSI-II

- New Software Interface: SCSI-II. Chapter 16 Jukebox Commands

• Library Management: Physical Volume Repository

- Input PVS and Provide Level of Intelligence

- Management Resource and Allocation of Bins and Drives

- Automatic Error Recovery

• Servers and Applications Provide Next Level

- Storage Sewers and Bit File/Client Servers

- Backup

_Y, l,. Odetics

Summary

What Odetics Can Offer the Market

• We Are and Will Be a Major Supplier of Robotic Libraries

Advancing Technologies

• By Year End, From Broadcast and ATL Products Divisions

- Four Different ATL Technologies and Five Products

- Cross "Breeding" of Technologies Across Divisions

• In the Future

- Broader Reach of Products and Markets Using Robotics

- Further Transfer of Technologies at Component Levels

IX)CUMENT NO9011002.2

TLILy, 1991

AIrL Predue, ta nq4e/,m

Odetics

2-119
2-120
_ °.-

® 0

Eo !i

®®_ _ _ _-

_'|_ E.-_ ".,

_ _ _

_" o= _ _

8 __ "-

'i

>:

'7

=.

2-121
PANEL DISCUSSION:

STABILITY OF HIGH DENSITY MAGNETIC TAPE

Moderator: Professor Mark Kryder

Participants: Bellcore. Ampex. Sony. Advanced Development Corp., NML-3M !

MR. SAVAGE: _We have come to the panel section of the afternoon session. Our panel

moderator this afternoon is Professor Mark Kryder from Carnegie Mellon University in

Pittsburgh, Pennsylvania. Mark has a respectable biography here, which I think I will read

because they are still making a few preparations there. ..... ' _

Mark received a B.S. Degree in Electrical Enginee_ fi'om Stanford in 1965, an M.S. in

Electrical Engineering from Cal Tech in 1966, and a Ph.D. in Electrical Enginee_ and

Physics from Cal Tech in 1970.

From 1969 to 1971, he was a research fellow at Ca] Tech; and from 1971 to 1973, he was

a visiting scienUst at the University of Regensburg, West Germany. From 1973 to 1978, he was a

research staff member and manager of exploratory bubble device rese_h at the IBM T.J.

Watson Research Center. In 1978, he Joined Carnegie-Mellon University, where he is now

Professor of Electrical and Computer Engineering and Director of the Engineering Research

Center in Data Storage Systems, which he founded.

Professor Kryder has over 150 papers and i0 patents in the field of magnetic materials

and devices. Currently, he is actively involved in research on magnetic and magneto-optlcal

recording technology. Mark, it's all yours.

DR]KRYDER: Th_ jbdve_ much. I hope we are go_ tO have some fun this

afternoon. The success of this panel in this aftemoon's activity really depends on the

audience. You know, the speakers are going to get up here and make a few statements; but it

really depends upon you, the audience, to challenge them and to provoke some controversy and

get some good discussions going.

So, i hope you are all primed and thinking about getting some of those controversial

questions out there.

What we are going to try to do _ to have a panel discussi0n On the archival

characteristics of various tape media. And we have representatives here from a large number

of organizations; and we will actually have an opportunity to hear from people talking about

chromium dioxide, cobalt gamma type materials, as well as metal particle and metal

evaporated type materials, as well as barium ferrite. '

And we will hope to see some comparisons of those; I hope to maybe find out what some

of the problems are. We may not come to any solutions here, but the hope is that we can

identify some of the problems; and maybe we can conclude that some of the problems that

people thought were there really aren't problems.

Anyway, we would llke to get the issues out on the table.

What we are going to do is this: We have a number of people to bring up here, and I have

asked each group to go no longer than 15 mlnutes--absolute maximum--in their preSentatfon.

There are really five groups; so, that means we will have an hour and 15 minutes of

presentations maximum.

And then. following that. we will have an open panel discussion.

2-122
Now,in orderto makeroomfor theviewgraphsandsoforth, althoughlater on we will

ask all the panel members to come up when we have the discussion session, I have decided to

have them here in the first row at the beginning; and then, we will let each one give the

individual presentation and then take their seat. And then, when it is time for the discussion,

everybody will come forward.

What I have tried to do is organize the session from the historical perspective forward

in terms of when various media were introduced.

So, the first person this allernoon whom I am going to have speak is Dr. Barbara Reagor

from Bellcore. She is Division Manager of Chemistry and Materials Science Research. She has

21 years experience in contamination and materials reliability in telecommunications and

data center environments.

From 1970 to 1983, she was at Bell Laboratories. From 1984 to date, she has been with

Bellcore. She has a B.S. in Chemistry from Monmouth College in New Jersey, an M.S. in

Organic Catalysis and a Ph.D. in Chemistry, doing work on pico-second laser spectroscopy,

from Seton Hall University in New Jersey.

Barbara will talk about the environmental impacts on mass storage systems, with

particular emphasis on chromium dioxide in the 3480 cartridge. Barbara?

ENVIRONMENTAL IMPACTS ON MASS STORAGE SYSTEMS

Dr. Barbara Reagor

Bellcore

DR. REAGOI_ To give you an overview, back in 1986, what brought my Bellcore group

into involvement with this was the appearance of an article of this nature saying that

chromium dioxide tapes would pose a toxic hazard for employees as well as environmental

disposal of the units.

(Showing of viewgraphs)

DR. REAGOI_ The companies that own Bellcore are all of the regional Bell operating

companies; and our use of data is quite extensive in data storage.

We basically must store for greater than ten years all of the telephone call transactions

that go through this country, all of the billing information, all of the operational parameters

of the switching equipment. And we were very concerned about the reliability of tapes, in

particular if there are questions being raised about their environmental robustness or in terms

of their toxic characteristics.

The types of long-term stability we are looking for are the impacts from indoor air

pollutants, heat and humidity, and also again this question of toxic removal.

We have heard a lot today about different tapes. (Change of viewgraph)

DR. REAGOI_ And I threw one of these in very quickly Just to give an overview of what

the magnetic metal oxide tapes were llke, where we have your metal oxide particles--iron oxide

or chromium dioxide--embedded in a polymer-based binder. That binder can be an elastomer

of polyurethane; it may have lubricants, dispersants or curing agents, as well as other

additives in it to give it its various properties.

And then, we have our polymer base, which is usually PET, polyethylene terephthalate;

PVC, polyester, or cellulose acetate material.

2-I23
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2-124
In doing our study, we approached this from the sense of trying to learn as much as we

could about the new chromium tapes. In 1987, we purchased seven different vendor products,

all chromium tapes, all 3480 IBM compatible materials.

And these are the tests we subjected them to: differential scanning calorimetry to see

how it responds to heat cycling and heat tests; thermal/mechanlcal analysis, where we look at

the stretching parameters as we heat and move this tape in use; thermogravimetric analysis.

And we actually developed a magneto- thermogravlmetric analysis technique, where we

could look at the effect of heating in the presence of a 150 Gauss magnetic field. We did the

magneto-hysteresis to see the impact of aging and chemical stressing on these tapes; and other

typical chemical analyses, with F'IIR analysis, extractions, X-ray spectroscopy, as well as

macroscopic investigations.

(Change of viewgraph)

DR. REAGOPc In terms of some of the thermomechanical studies, what we would look at

is a glassy type material at room temperature. You could slowly extend the materials, strain

them as you start to heat. You would then see stress relaxation of the coatings on th_ physical

binders.

And finally, ff we got to about 200 ° C, we would start to see melting of the actual binder

and substrate materials. And we looked at the effects this had on the magnetism.

(Change of viewgraph)

DR. REAGOR: If we ran a _ analysis, we would start to see some very interesting

things. With the TGA, we can find the Curie temperature, where we lose all magnetism. That is

where the chromium tapes do have a disadvantage over iron.

In a chromium tape, as you scan the temperature range, when you reach about 120°C,

you actually lose magnetism--at the Curie point, about 125°C for these tapes. We could actually

monitor this with and without magnetic fields.

We would watch the deterioration of the actual substrate; comparing that to the case of

an iron oxide tape, where the Curie temperature is 600°C, you have no loss of magnetism with

that type of system.

(Change of viewgraph)

DR. REAGOR: To correlate it a little bit better. We could even do some interesting things

where we could identify the actual degradation of the materials using these types of techniques.

We can see the effect of alignment of the chromium particles at the Curie temperature;

we actually start to see a disalignment of the particles, a loss of magnetism, as they become

mobile within the matrix of the binder.

As you reach the Curie point, we can look at the actual degradation. And a lot of work

was put into using this material to actually analyze the tapes.

One of the things that we were able to learn from this--and it can be shown here --

(Change of viewgraph)

DR. REAGOR: Is we would look on when the alignment onset changed--at what

temperature. At what temperature do we actually see the particles on the tape start to move and

to lose alignment from a magnetic field? And in all of the tapes, the binder onset for alignment

were showing up in about the 83 ° C range. We were able to obtain, like I said, through this

2-125
methodthe Curietemperatures;and it showsyou right herethat T- 5 was actually an iron oxide

tape and not a chromium dioxide tape.

2 22L _ :_

From these types of information, from the weight gain and the loss of weight, depending

on whether we have magnetic fields in place, we could determine the actual percent of

substrate, the percent of metal, in the systems. We could take these alI_the way f0total

combustion; and in doing that, what we actually came up with was almost all of the tapes really

were between the 30 and 35 mm thick PET films; and they had between 2 and 4 mm of coating

in terms of the metal oxide. Yesterday, you heard a lot about the coercive force, about applied

fields.

(Change of viewgraph)

Y : , " , :

DR- REAGOI_ I put this up Just as a way of explaining some ofthe data I_ going to talk

to you about. When we do magnetohysteresis measurements, what we gain out of this hysteresis

loop is that we can then get our remanent magnetization measurement. We can see our

saturation magnetization; we can develop and measure the tape, and the surface roughness

drastically changes the frictional drive.

PARTICIPANT: How long was the aging?

DR- REAGO1_ i5 to 30 days. 85 degrees. This is not unreasonable for being in the back

seat of your car On a humid day, and transportation was an issue. It is not unreasonable if you

are in an environment that is in a disaster situation; and we have to maintain the possibility

of that.

We also did, Just looking at a variety of tapes, and we did studies of this nature, where we

kept the temperature low and high.

(Change of viewgraph)

DR. REAGOR: We changed the hun_dity; we actually measured this magnetic weight. It

gives you a feeling for how much magnetism is still retained in the tape and looked at the

percent losses that we would see.

And again, situations that developed'-massive changes--are shown here. At low

temperature, basically Just a little bit above room temperature, the humidity alone and the low

temperature alone don't really hurt us unless it is an acidic medium.

If we have acidic conditions at 30 °, yes, we will see 20% loss of magnetic ability. If we

are on the other side, if we are in high pH conditions --basic conditlons--we actually only see 5

percent for the sam e situation.

Once we go into the 85 ° areas, we are starting to see losses in all of these tapes for the

conditions. These are short-term exposures--two hours--for the tapes.

If we look at, again, three different tapes--this is the iron tape--again T-5; and that one

behaved very, very well no matter what pH. It was actually the best performer of the group,

which still says something for the iron oxides.

(Change of viewgraph)

DR. REAGOR: T0 give you a feeling for the analysis of this and Just what we did in terms

of looking at the tapes, in doing the elemental analysis of the materials, We f6und-a_oTthe

chromium tapes still contain iron. That may be a trade secret; I'm not sure. But basically,

there are still iron magnetic materials in all of these tapes except, like I said, for theT-5 which

did not have any chromium,

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We looked at the effect of iron-to-chromlum ratio and its effect on being changed as we

dulled the tapes. Dulling was caused when one put these through the environmental stressing

situations.

And again, you can see the ratio of these peak areas was changing slightly as we go in

terms of the shiny and the dull; the ratio is changing because we were basically corroding the

metal, forcing it deeper into the surface. And with the technique we were using, we were trying

to do a surface ratio penetrating very lightly into the surface of the tape structure. And this

gave us a good feeling for the actual surface composition being changed by the actual study.

{Change of viewgraph)

DI_ REAGORz All of this work, putting together, basically brought us to a proposal for

what the degradation mechanism was and that there were two mechanisms that could impact

the tape. One was a chemical one, where we could have an acid catalyzed hydrolysis; it wasthe

binder in all cases that was allowing the loss of magnetism as well as an interaction of the

particle surface with the binder that could reduce some of the magnetism.

We were seeing in a physical sense that thermally induced disordering where the

particles could mlsalign and we would lose their magnetic effect were showing some entropic

relaxation,

What we saw in these cases was that these two types of degradation mechanisms would

reduce the adhesion of the magnetic particles to the tape. And if you do that, then your

alignment and your magnetic fields would have less effect for read/write. We would see it

disrupt the particle array, and we would see orientation changes in the tape; and that was

critical ff we were in a longitudinal tape reading mode and all the CrO2 particles are going off

axis.

And the thing with the chromium that we liked so much was these elongated needles

that gave us our best magnetic reading capability. And now, all of a sudden, IYn changing the

configuration of that needle, and I'm not using its long length; I'm now using its width because

it's turning away from the longitudinal axis, that we can see that that can disrupt our ability to

read/write.

And then, we were Seeing that we could actually create defect sites, that as you read

across the tape, these disorders--the small amount of corrosion--could lead to problems.

This work was actually published in a paper, and I'll Just give you the source. It was

published in the book by Mittal called Polymers in Iruformation Storage Technology. * The key

team leader here was Trevor Bowmer, and he published it as "Characterization and Hydrolysis

of Magnetic Tapes."

Our lawyers would not Mow us to use the term "3480 '° anywhere in the publication

because they thought that was a trade name and that would look as ff we were doing a product

analysis. So, there is this paper; it was published in 1989 based on a very large amount of work

that was done on these tape materials.

Additionally, we did solvation studies and extraction studies; and we looked at the

solvent impacts on all of these different tape materials. The one material that affected all of

the tapes in terms of long-term exposure, we had five 15-minute exposures to different types of

solvent systems and then greater than 24.

* K. L. Mittal, ed: Polymers in Information Storage Technology

(New York: Plenum Press, 1990)

2-138
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We saw either no impact, or we saw a small amount of deterioration of the binder. The

one product that did impact them all was halon-211, in a long-term exposure; five 15 minutes,

no change; 24 hour soak time, a noticeable deterioration in the binder of the tapes.

I raise this right now because halon-211 is leaving us, and we are going to see some new

halon products; and it is going to be vital that the studies of any _ape medium be done with

these new halon replacements to ensure that we don't have short-term exposure changes for

those materials.

That was the basis for the talk I had provided for the conference; and one additional

thing I wanted to bring up is a concept for you.

(Change of viewgraph)

DR. REAGOR: At this point in time, we use the chromium-based tape in all of Our data

centers. I have 75 maxicenters across this country with more than i0,000 DASDs in operation

at this tlme; and those 10,000 3380 DASDs are dumping to the 3480 magnetic tape. And then,

that goes into our storage.

The nuinbers, I can't tell you. I can't tell you the number of tapes, but it is an u_odiy

large number. And we are required by law to store this magnetic media minimally ten years.

And it has everything you can imagine on it in terms of a telephone call placed in this country:

date, time, to/from, what carrier it went through, and the whole bit.

And that is an awful lot of data that needs to be stored and retrieved; and so, from a user

standpoint, we are very concerned.

The difference I see is that this is the concept of a typical data center, like our typical

data center, like your typical data center. A controlled environment, filtered from a major

system, and then uniquely filtered with high change rates inside.

We know that they are not highly contaminated areas yet.

(Change of viewgraph)

DR- REAGOI_ Sometimes, this is typical of what they look like in terms of

contamination.

The difference between a data center and a telephone switching office is basically in the

particulate level and the temperature windows. From a particulate standpoint, this gives you a

good feeling of what a low activity and a high activity data center--D.C.--versus a telephone

center office, in terms of low activity. _ . = "

Our data centers in those spaces stay under the i0,_ particle per cubic foot at .5

micron; so, basically, a 10,000 foot clean room.

High activity in a normal central office is still below the 100,000 that we set for

computer s _t___dards. i b_ this =up since we are now moving the p_essing and storage :

capability of the computer center, and it is being merged with the electronic switch. Ahdthis is

happening on a daffy basis.

When you pick up your phone today and want to look at caller I.D. or have the various

calling features, that is being done on the switching product with the 3480 line, some products

with a 340 megabyte drive system, on- line storage of data right there in the switching office.

The difference that we see for the future is that that move to have s{orage within :the

central office is going to be greater, but we are going to have a higher need for data storage and

data manipulation within the management of the system.

2-142
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We are going to have user influenced telephone systems, that as a user I can, with the

touch of a dial, change what I get for information or change where I go in terms of pathways

that I can select one carrier one day and another carrier another day. To do that, you now have

to maintain a computer system in this environment because these are the standards for

telephones.

The operating environment is from 40°F to 100, a minimum of 35 and a maximum of

120. The nominal temperature will swing 12 degrees an hour on any given day and will cycle in

that range.

There is a humidity operating range of from 20 to 55% humidity; and it will float and is

allowed to go as low as 10 and as high as 80, and the projections are now to go as high as 90.

And in that environment, computing equipment and storage media must work. And so, we are

looking at.some interesting changes.

(Change of viewgraph)

DR. REAGOR: In addition, I have brought the environmental standards for gases and

for contaminants. In both our data centers and our central offices, we only control

particulates. The rest of it--whatever is outside --comes inside,

From the standpoint of robustness, we look at three ingredients that we recommend

vendors must be able to withstand: 25 micrograms of dust per cubic meter of air;, volatile

organic compounds on the order of 1,200 parts per million; and ammonia to the level of 500

parts per billion. Ammonia is generated by people, and it's in the products we use to clean our

floors: and it will always be there. The rest of these gases are typical 95% level, short-term

exposure possibilities.

And all of these gases that are outside a data center or central office will be pulled inside

that data center and central office, and their resident lifetimes are a whole lot higher than

people realize.

I was very happy to hear the comment on ozone because we have measured the ozone;

and depending on the outside air strategy of a building, you can have 80 percent of the outside

level indoors as a constant level during the day. And that is a critical amount if your outdoor

level happens to be 200 parts per billion.

And ozone is something that we actually have in our standard test now. And for our

purposes, we have ozone levels as even potentially having a maximum of 500, which is

everything outside plus the fact that I have laser printers and a variety of other products inside

contributing to that type of level.

So, my words to you at this point are: We see chromium as a little bit less sensitive or

less robust than the iron, but it is still good in our environment; but it is more of a word of

wisdom to you that, for the future, we are going to need some very robust materials because we

are going to be living in two environments.

(Applause)

DR. KRYDEI_ Write down your questions and make a note of them to yourselves because

we are going to proceed all the way through the presentations before we entertain questions.

The next speaker will be Darlene Carlson. Darlene is a chemist working as Manager of

Operations Support in the 3M National Media Laboratory. She has worked in magnetic media

for 18 years with broad-based experience in media formulation and applications development.

2-145
Darlenewas the principal investigatorin the developmentand introduction of 3M

metal audio tape in 1978. In recent years, Darlene has developed hlgh-density digital recol:ding

tape for Government applications.

Darlene will be talking about the stability of cobalt-doped gammaferric oxide tape.

_T_BILITY OF _0BALT-DQPED C._AMMAFERRI_ OXIDE

Darlene Carlson

3M National Media Laboratory

MS. CAkRLSON: Good aRemoon. I would llke to talk to you today about cobalt-doped

gammaferric oxide; and you have heard a lot about a lot of different products out on the market

today.

J

(Showing of viewgraphs)

MS. CARLSON: The question is: Why are we so interested in cobalt-doped gammaferrie

oxide? .................

If you consider the entire recording industry, cobalt-doped gammaferric oxide is

basically an order of magnitude more in production than any other medium that is in the

market place. R is a work horse; it is the cost driver. It is what makes the media

manufacturers, both here and in Japan, chum. This is the driving force.

So, you really have to underst_dwhy people are involved in cobalt-doped materials.

The question is always: What is the stability of the materials?

(Change of viewgraph)

MS. CARLSON: _t i_e dohe is given you an overview of the various types of recording

media. And what we are talking about is basically a consumer's report type thing, looking at

temperature, humidity, the pollutants in the Class II Battelle environment, and then a

combination of those two_

And what you can see is that the normal iron oxide, which is your typical

instrumentation tape, is better than the cobalt-doped iron oxide. Now, I'll get into the reason

why that is; but it is also better than the MP and the metal evaporated and the cobalt chromium

that is coming down the line.

{Change of viewgrapla)

MS. CARLSON: What I'm talking about here is the surface-modified or surface-adsorbed

cobalt material; and what we have is an interior material of g-ferric oxide in there, which is

the normal 300 Oersted instrumentation tape, that has been surface-modified with cobalt,

which gives you a very interesting engineering material.

And if you rememb.er John Mallinson, who was talking about the paranoia that people

have in the recording industry because they are concerned about the next generation of thing

that will overcome the recording media, my contention is that the reason why we are still with

magnetic recording media is the versatility of this particuI_ir Species.

We have a coercivity range of 450 to 900 Oersteds; and we have some control over the

aspect ratio and the surface area. So, this is a very interesting engineering material, which has

allowed us to 'fend off" all the different media recording technologies that are out there.

2-146
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Recording Bit Density Comparison

Linear, Low Density: 2060 bits per inch, 20 rail width; 165X.

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2-149
(Change of viewgraph)

MS. CARLSON: It is used in a wide variety of systems, both in fixed transverse and

helical scan material and a lot of different media formats. And it is coated on a lot of different

thicknesses of materials.

And you can see that it has a wide range of capacity for package; and again, this is in

gigabits, not glgabytes. And, depending upon the application, the durability has a wide range.

Now, one question is: How long can you archive this material?

(Change of viewgraph)

MS. _N: Unfor[unatdy, this particular _e_aph i_n_t very ciear:_but what t

would llke to do is do a bit of a comparison. This is a 2K bit, this is just one bit right here. And

this is a -- technique of a search track on a digital recording system: _: - _:- ;::

These bits are 20 mils wide, and these represent probably a_x_ut throe _es as large as

your 6250 bpi material that everybody is used to. But you can see that this parUcular ,- shows

you a 45K bits. So, when you ask: what is the archivabflity of co-bb-_- od_ed_hiat_?, it really

depends upon your bit density; and the implementations and archivability of a 2K material or

6250 material is going to be much, much different than a 45 Kfci or as an 8 millimeter, we are

going up to 75 Kfci.

So, you can see that these bits are actually getting smaller as you evolve into different

products. - ....

(Change of viewgraph) _:_: : .:

• Ms, ON: " ....... Similar to what Barbara was talking about, magnetic tape components

have a lot of different contributions that could impact archivabflity. We have a coating layer

of polyester, and some people have backcoating

And each of these components can be the weakest llnk in any archive system. Now,

what I would llke to do is take a broad-brush approach on what can happen to the various

individual components in a tape system.

{Change of _ewgraph]- ..........

MS. CARLSON: Ifyou iooifat the SuBs-trate, what you are interested in is the

dimensional stability and how that affects crossplay.

If you look at any ANSI standard or SMPTE standard or MIL standard, what we

normally do is define the tape format on the tape. That's the system in which the head lays

down your track of information. , _ -

Because of either tape shrinkage or tape creep, which is involved with tension on the

tape, you can actually have the polyester changing so that your recorded track is outside of that

tape standard. And therefore, you will not get crossplay; and sometimes, it can be so bad that

you can actually lose self play.

So, dimensional stability is well known, and it is a concern in any archive

environme nt.

(Change of viewgraph)

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MS. CARLSON: Another thing that is of importance is the hydrolysis. Barbara talked

earlier about hydrolysis of the binder and compared instrumentation tape with various tapes;

and this is Co-doped material; and what you can see is that hydrolysis is still with us--it is

alive and well.

And this is a solvent extraction at 58 ° C/90% RH; and we are looking at two different

vendors of VHS tapes, three different vendors of S-VHS and D- 1.

And you can see that, after 50 weeks--which is an extremely long period of tirrae--that we

still have hydrolysis. Now, the purpose of this study is that we have a family of curves that we

are developing, and we are developing various equations from them; and we will have models

= to predict for all the various materials.

But you can see that in the cobalt-doped materials, we do have hydrolysis; and we will

have to manage for that change.

(Change of viewgraph)

MS. CARI_ON: If you remember the earlier slide, I told you that the cobalt-doped

material is not as stable as other things like g-ferric oxide. And the reason for that is because

of the coerclvity change.

What happens is that the cobalt actually diffuses into the g- Fe203; and what you do is

you lose coercivity. And again, what we are plotting here is the coercivity change at 58 ° C/90%

RH at up to 50 weeks.

And you can see that there is a variation from different types of cobalt to how fast or

what the mechanism of the cobalt migrating into the g-Fe203 is.

(Change of viewgraph)

MS. CARLSON: Now, in contrast, the fR, which is the measure of the remanent

magnetization, is very, very stable; and I don't know ff you remember this from Barbara's talk,

but chromium is much worse than this. And this is basically within the measurement error.

(Change of viewgraph}

MS. CARLSON: In summary, we have to be careful about how we specify any archive

requirements. You can archive cobalt-doped gamma materials for up to ten years. Now, the

caution that I have is that you have to retension and clean the tape.

In most mass storage situations recertification is not an issue because what you are

doing is you are recording on one tape or reading from another or whatever. But if you are

reusing a tape, it should be recertified.

The archive requirements are system-specific, specifically because there is such a wide

range of requirements out there; and each system has its own peculiar way of being

implemented.

And many times, a tape vendor recommends a certain range of temperature and

humidity controls; but the user environment, as Barbara was saying, is outside of that. We

recommend never putting a tape outside of a 70% RH environment.

And as we heard today, they realize that we will store at 95% RH. So, the question is:

what implementation procedures should we utilize if we are storing at 95% RH? And that is

what we are in the process of developing.

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I know that there are going to be some network managers here who would llke to throw

tomatoes at me at this particular moment ; but even with local area networks and wide-area

networks, media will require shipping. And the analogy I always cite is: Remember when they

sald that we were going to have a paperless office? the same thing here. Media will require

shipping; and therefore, we have to be concerned about how it is being shipped.

And we also have to be concerned about anomalies such as fire, water damage as a result

of people spilling coffee or whatever, and various other shipping impacts such as DC motors,

erasing the tape.

So, we have to be able to do a recovery from these types of anomalies and events. And we

have been involved with some tape recovery operations.

That concludes my talk.

(Applause)

DR. KRYDER: We will hold the questions until the discussion. Thank you, Darlene.

Our next speaker is Kazuhiro Okamoto. He obtained his M.S. Degree In Physics from

Hokaido University. He has been working at Sony for the past eight years. He is a materials

engineer working in the Magnetic Particle Development Group.

The title of his presentation is "Stability of Metal Particles/Metal Particulate Media."

_TABILITY OF METAL PARTI(_LES/METAL PARTIC_.ATE MEDIA

Kazuhiro Okamoto

Sony

MR. OKAMOTO: Thank you. Today, I would like to talk about the study of metal

particles and the metal particulate media.

2-159
N93-16329. 

StabUity of Metal l_a_e, le and Metal Particulate Media

Kazuhiro Okamoto

Sony Magnetic Products Inc., TagaJo, Miyagi, Japan

1. Introduction

Metal particulate {MP} video tape Was launched for 8 mm video tape in 1985.

Since then MP tapes have been applied to several consumer formats and instrumental

formats because of its superior electrical performance. Recently data storage media,

such as DDS, and D - 8, have started employing MP tape.

However, there are serious concerns with archival stability of MP tape

particularly in the case of data storage use, as metal particles essentially have problems

with chemical instability and are susceptible to oxidation and corrosion. Although

there have been some studies about the archival stability of metal particles or MP tapes

(I) - (3}, a clear understanding has yet to be reached.

In this paper, we report the stability of magnetic properties of current metal

particles, and then discuss the new technologies to improve the stability further.

2. Stability of Current Metal Particles

A metal particle is composed of three layers. Pure iron core with os=222 emu/g

is covered with a passivated iron oxide layer, and it is covered again with a ceramic

layer composed of Al and/or Si compounds. The outer two layers prevent the oxidation

of the iron core. The important role of the surface ceramic layer to the stability of

metal particles is shown in Fig. I.

The stability of metal particles is improved still more when they become part of

the tape, since they are covered uniformly with binder molecules during the mixing

process (Fig. 2}. Fig. 3 shows the archival stability of the RF-output of Betacam tape.

Little degradation is observed even after long te_ st0rage in a 45'C, 80%RH

environment. So, from a practical viewpoint the current MP tape has sufficient

stability due to the multflayer protection of the iron core.

2-160
3. NewlyDevelopingTechnologies

3-1. DenseOxideLayer

Themorphologyof pureiron coreis thought to bemeasuredwith X-ray

crystaUitesizeDx. Theagingeffectsof os and Dx of current metal particles under 60"C,

90%RH environment is shown in Fig. 4. The initial degradation of _s occurs without

damage to the morphology of iron core. This fact indicates that the degradation of _s

begins with the destruction of the oxide layer. Therefore the formation of a uniform

and dense oxide layer would promise improvement in the stability of metal particles.

Fig. 5 shows the comparison of the degradation ratios of flux density between

current MP tape and improved MP tape which utilizes new metal particles with a dense

oxide layer under the storage conditions of 65"C, 90%RH. The improved MP tape is

twice as stable as the current one which is already stable.

3-2. Anticorrosive Agent

In order to improve the archival stability to the highest degree possible, we are

researching anticorrosive agents. A low molecular organic compound would be selected

as an anticorrosive agent to minimize the decrease of magnetization by the use of nonmagnetic materials. The organic anticorrosive agent which is adsorbed onto the

surface of the metal particles changes the hydrophflic surface into a hydrophobic

surface and cuts off direct contact with oxygen and moisture in the atmosphere.

The results of the aging test of the currently used metal particles, the improved

ones (with a dense oxide layer), and the anticorrosive agent treated particles are shown

in Fig. 6. The stability of metal particles are amazingly improved through the

application of the antlcorroslve agents. The degradation ratio of treated metal

particles is comparable to that of magetite particles which have the same size.

2-161
4. Stability of Coercivity

Thecoercivityof metalparticlesusually showsalmostno changeor a little

increasefrom the agingtesL The degradationof coercivity,however,is observedonly

when the magnetizationdecreasesextremely.

5. Conclusion

Currentlyusedmetalparticlesarestable,as theyhaveprotectionlayersof

ceramiccoatingand passivatedoxide. Thereforethe MPtapehas sufficient stability for

practicaluse. In orderto improvethe stability further, newmetalparticleswhich have

a uniform and denseOxidelayerand an anticorrosiveagentareunderdevelopment.

References

(I)

(3}

T. D. Lee, S. Hu and N. Madulid; IEEE Trans. on Magn. MAG-23 {1987) 2880

D. E. Speliotis; IEEE Trans. on Magn. MAG-26 (1990) 124

Y. Yamamoto, K. Sumiya, & Miyake, M. Kishimoto and T. Taniguchi; IEEE Trans.

on Magn. MAG-26 (1990} 2098

2-162
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2-164
DR. KRYDER: Next, we have a two for one deal. Ampex is going to split their time

between two speakers; they promise to keep both their talks within the 15-minute time limit.

The first talk will be by Allan Hadad. Allan has a B.S. Degree in Chemistry and an M.S.

Degree in Materials Engineering. He started his professional career as a synthetic organic

chemist working in the application of high-performance polymers in the wire and cable

industry.

Allan began working in the recording industry in 1974 as a formulation development

chemist. He has developed various tape formulations for both consumer and professional use.

He has participated in the application and introduction of products based on the evolution of

new magnetic materials, from cobalt-adsorbed iron oxides to iron particles.

Allan has also managed Ampex's metal-evaporated tape program. AIlan's current

assignment is Manager of Formulation Development for Ampex Recording Media Corporation

in Redwood City, California and Program Manager for an all metal particle development effort

in both Redwood City and Opalaica, Alabama.

Allan will be speaking on an empirical approach to predicting archival stability and

primarily discussing metal particles.

2-165
AN EMPIRIC_kL APPROACH TO PREDH_FING ARCHIVAL STAB_.rrY

Mr. Allan Hadad , :

Ampex Corporation

MR. HADAD: Good afternoon. Of course, John and I are going to be splitting the time;

but we never did come to an agreement about where the split would be. So, since I'm here first --

(Laughter)

MR. HADAD: I would also like to th_Dr, Harihamn for inviting me. He called me

about a month ago; he asked me what I thought about the concept of free speech. I said I agreed

with it; and he said: Good. I'd llke you to give one at this conference. So, here I am.

(Laughter)

{Showing of viewgraphs) .......

: MR. HADAD: I:would iike to talk about the stability of high-density media, particularly

of course metal particles, that I have been involved with pretty much since 1978.

I like to separate environmental stability from archival stability. I feel that most of

the testing that we have done so far--and much of the data that you have maybe even seen

today--is environmental stability, discrete conditions in which tapes have been exposed. You

have seen some data. I call that a user condition, perhaps during acquisition, as opposed to

long-term storage.

Archival stability, I think, has to be determined by predictive techniques,

mathematical modeling, taking a lot of data from a variety of environmental exposure

conditions, sort of lumping it together and building an expression, to be able to predict what

will happen at any temperature and humidity condition.

What will the environmental stability of a tape be? How long will it really last? What's

the lifetime of tape?

So, what I am going to present here is some data that we have acquired on

environmental stability, basically to give the users confidence that under a certain variety of

conditions, we feel very confident ourselves that metal particles do produce a viable recording

medium for high- density information.

I will follow that then by an empirical approach that we have developed and are trying

to propose as really the means or the vehicle to predict what the lifetime of tape will be.

{Change of vlewgraph)

MR- HADAD: When we first got into the metal particles, we worked initially a great deal

with the particle manufacturers themselves. They have made a lot of changes for us, as well as

for all the other magnetic tape manufacturers, to produce much more stable particles, more

passive particles.

Just some data that wek, e got. It was collected between 1987 and 1990. Three different

particles that have been evaluated in our laboratory since 1987; and basically, the conditions

are essentially ambient: 22 ° C/40% relative humidity.

2-166
As youcan see, obviouslythereareavariety of materialsavailablefrom the particle

manufacturers;but in general,whatweareseeinghereis that afterthreeand a half years--and

this is nakedtape;it is not protectedby acassettecase

(Changeof viewgraph)

MR.HADAD:Tapesexposedto the ambientenvironmentthat, afterthree and a half

years,haveexperiencedlossesof aboutor lessthan 2percentin Bm.

(Changeof viewgraph)

MR.HADAD: Goinga little further then, lookingat someof thoseenvironmental

exposureconditions,I_¢egot a charthere. Wearelookingat four differenttapes,commercially

availabletapes--someof our own, someof our competitors--atthree differentenvironmental

conditions.

Ambient again,30° C, 70% relativehumidity, and 54° C, 85%relative humidity--falrly

extremeconditions. AlthoughI believethat certain usersmayfor short periodsof time have

exposedthe tapesto theseconditions,especiallyduring initial acquisitionof data,or perhaps

through transient activities,asDarlenesaid--afire, a sprinkler systemgoingoff--that often

tapescanbeexposedto someof thesemoreextremeconditions.

Thebottomline: theloss in Bm. Obviously, for ambient conditions again, we see some

.variation; but basically, around a 1 to maybe a 3 percent loss, after nearly six months

exposure.

Moving up to the 30 ° C/70% relative humidity, losses on the order now--it depends on

the manufacturer--around 2 to 3 percent loss in Bm again.

And then finally, the very extreme case, where now we start to see very rapid or much

more devastating losses in magnetic performance, although again we wouldn't certainly call

that an archival or storage condition.

Now, perhaps for certain short amounts of time, and it could be tolerated maybe on up

to six months, or maybe a couple of weeks, in an environment like that, that data could be

collected; and acceptable losses in magnetic performance would occur.

(Change of viewgraph)

MR. HADAD: Going out a little bit further, some D-2 tape, again under ambient

conditions, six months worth of data. And we see somewhere around a 1 dB loss after 24

months--two-year data now.

In this case now, we are looking at tapes that are protected by the cassette. We are

moving a little bit further along now where, on the tapes themselves, there is an extra level of

shielding. Of course, the particles degrade the fastest; we saw some of that in the paper given by

the gentleman from Sony.

We put it into the tape system; the binders give it a degree of shielding. Now, it's inside a

cassette. There is an additional degree of shielding. Two-year data then, around a dB loss under

ambient conditions for this particular sample.

Of course, there is one thing about all of this. If you look at two and three-year data,

that's the old stuff now--rlght? Improvements have been made since.

(Change of viewgraph)

2-167
MR.HADAD:A real quick lookat errors. This seemsto bethe real key. Again,about

six-month dataand essentiallywith somevariability of three of thesesamplesat ambient

conditions,22° C/50% relativehumidity, with nodramatic changein the errorsperframe

herewith threeof the manufacturers.

Oneof the tapeshereapparentlyhad somedebrison it that wasactuallybeingremoved

with the repetitivetestingoveraperiodof time. Ofcourse,wehaveseenthat before.

(Changeof viewgraph)

MR.HADAD: Undermoreextremeconditionsthereis an increasein errors,again

cassettes.Were gotonehere--actually,it wasthe sameonethat was cleaningup-- but fairly

raggedout hereat theend.

But in generalagain,noreal changein the error countat 30° C/70% relativehumidity

for a periodof almost six months.

Okay. That's environmentalstability. That's not reallykinetics. As a chemistand as a

materialsscientist,i like to reducethings downto mathemati_6ai expressionand predict: How

longwill thesetapesreally last under normalstorageconditions?

Wehaveto comeup with a coefficientthat relates;you cansort of additivelycombine all

the exposure conditions and determine how much time is really left on this tape.

(Change of viewgraph)

HADAD: My favorite ch_ is the psychrometrlc chart. For those of you who have

not seen it, it basically relates temperature to water content in air. Relative humidity are the

curved lines. Absolute humidity are the horizontal lines.

What we have done is through an experimental design, these points are actual

conditions that we have exposed powders to. Now, you start at the front end, and you adjust the

powders themselves; there are about 12 conditions here. You have to do a multitude of testing.

Powders are subjected to these temperature/humidity combinations for periods

extending up to several months. Data is collected periodically; a curve is drawn of the

degradation behavior and the slope of that line is determined. That's the degradation rate.

Those degradation rates at each of these points we will put into the computer, crunch it,

and a mathematical equation was generated, describing -

(Change of viewgraph)

MR. HADAD: degradation rate as a function of, in this case, the silicon content of the

powder that we are looking at as a variable, relative humidity and temperature, cross products

between those and the square terms.

(Change of viewgraph)

MR. HADAD: We have a nonlinear equation that allowed us to generate lines of

constant degradation rate, if you will, as a function of temperature and humidity for a given

particle and gives us the ability now to predict long-term behavior at any

temperature/humidity combination within the experimental region.

What these numbe_ _e, again, are lines 0f Constant degradation rate. One thing it

shows is, that the relative humidity is the big driving factor in degradation of iron particles;

temperature is not as great a factor until you get below this critical value here whereas say, you

increase temperature, degradation rate does increase.

i

E

2-168 z
N99-1 .330

AN EMPIRICAL APPROACH TO PREDICTING LONG TERM BEHAVIOR OF

METAL PARTICLE BASED RECORDING MEDIA

By

Allan S. Hadad

Ampex Recording Media Corporation

Redwood City, California

Narrative

Submitted for the

National Space Science Data Center's

Conference on

Mass Storage Systems and Technologies for Space and Earth

Science Applications

Goddard Space Flight Center

Greenbelt, Maryland

July 23-25, 1991

2-169
!i
AN EMPIRICAL APPROACH TO PREDICTING LONG TERN BEHAVIOR OF

METAL PARTICLE BASED RECORDING MEDIA

Alpha iron particles used for magnetic recording are prepared through a

series of dehydration and reduction steps of _-Fe203-H20 resulting in

acicular, polycrystalline, body centered cubic (bcc) _-Fe particles

that are single magnetic domains. Since fine iron particles are

pyrophoric by nature, stabilization processes had to be developed in

order for iron particles to be considered as a viable recording medium

for long term archival (i.e. 25+ years) information storage. The

primary means of establishing stability is through passivation or

controlled oxidation of the iron particle's surface.

The usual technique of producing the protective layer is through reoxidation of the iron particle's surface after synthesis starting with

a mixture of 0.1% 02 and 99.9% N2. The oxygen content is slowly

increased to 20% (the composition of air) so as to maintain the reaction at room temperature. This results in a particle that is stable in

air provided it is not subjected to any form of i) mechanical abuse

that could disturb the outer layer, or 2) source of heat that would

initiate combustion.

PRECEDING PAGE Bt.AH,_ NOT FILMED

2-171
The nature of the passive layer on iron particles has been found to

consist of either Fe304, y-Fe203 or a mixture of the two. The thickness

of the passivation (or total) oxide layer is typically about 3°0 nm.

The condition of passivity slows down the oxidation of iron, but, the

formation of the iron-oxide layer around metallic iron particles does

not preclude further oxidation. The continued stability of iron particles is controlled by the integrity of the oxide layer and the

kinetics of diffusion of iron ions through it.

Since iron particles used for magnetic recording are small, additional

oxidation has a direct impact on performance especially where archival

storage of recorded information for long periods of time is important.

Further stabilization chemistry/processes had to be developed to

guarantee that iron particles could be considered as a viable long term

recording medium.

In an effort to retard the diffusion of iron ions through the oxide

layer, other elements such as silicon, aluminum and chromium have been

added to the base iron to promote more dense scale formation or to

alleviate some of the non-stoichiometric behavior of the oxide or both.

The presence of water vapor has been shown to disrupt the passive

layer, subsequently increasing the oxidation rate of the iron.

2-172
A study was undertaken to examine the degradation in magnetic properties as a function of both temperature and humidity on silicon-containing iron particles between 50-120°C and 3-89% relative humidity. The

methodology to which experimental data was collected and analyzed leading to predictive capability is discussed.

EXPERIMENT

To study the effect of temperature and humidity on the stability of

passivated iron particles as a function of silicon content, three

particle batches were prepared from the same precursor containing 0.81,

0.95 and 1.12% silicon by weight.

As stated earlier, the oxidation process of iron particles is diffusion

controlled. The increase in oxide thickness is determined by how fast

iron ions can migrate to the surface (passivation kinetics). It is

assumed that the reduction in as is proportional to the oxide thickness; therefore, Fick's second law of diffusion for concentration

dependent systems can be applied:

whe re:

Y2=Dt

Y = diffusion distance in cm

D = diffusivity in cm2/sec

t = diffusion time in sec.

2-173
For this analysis, the data are plotted as specific magnetic moment

versus the square root of time. The resultant slope is therefore the

rate of degradation expressed as EMU/gram-sec 0.5 for a given temperature and humidity condition.

Analysis of the interactive effects of temperature, humidity and percent silicon on the degradation of magnetic properties of iron

particles were determined using a statistical experimental design package run on an IBM AT compatible computer. The characteristic measured

was the log10 of_ loss per second O'5 (rate of degradation).

The procedure of data analysis' consists of selecting an initial

mathematical model (usually a quadratic equation to analyze interaction

and curvature effects of the form Y = CO + ClX 1 + C2X 2 + C13XIX 3 .... +

C11X12 + C22X22 .... ) where Cn is a constant and Xn is the level

setting of the respective factor. The model is then used to "fit" the

data.

RESULTS AND DISCUSSION

Dry Conditions. The first series of oxidation rate experiments were

run at the "dry" conditions for the seiected temperatures. Oxidation at

various temperatures allowed generation of os vs. time curves for iron

particles containing 0.81, 0.95 and 1.21% silicon sample at various

temperatures.

2-174
Figure 1 shows the change in specific magnetic moment with time for the

1.12% silicon sample at various temperatures. As temperature increased,

the rate of degradation of os also increased. Differences in the rate

of degradation at a given temperature between the three samples studied

containing different amounts of silicon are slight, indicating that the

iron particles all behave the same at low humidity, independent of Si

content or initial o s value.

Activation energies for degradation of the 0.81, 0.95 and 1.12%

silicon-in-iron powder samples were determined to be 0.383, 0.263,

0.333 eV, respectively when the rates of degradation were plotted

against the absolute temperature (Arrhenius plot). Thus, the energy

requirement to initiate the oxidation reaction for the various

Si-contents is essentially the same and all degrade at essentially the

same rate as a function of temperature. However, these activation

energies are only _10% of the value for diffusion of iron through any

of the possible iron oxides. The implication is that the primary mechanism for the loss in magnetic properties is not due to lattice

diffusion but rather diffusion along some short circuit path such as

linear or planer defects present in the oxide shell.

Moisture Effects. Magnetic moment loss is shown as a function of

humidity at constant temperature (70°C) for the 0.81, 0.95 and 1.12%

silicon samples in Figures 2, 3 and 4 respectively. As the humidity

increases, the rate at which the magnetic moment degrades increases

markedly with decreasing Si content.

2-175
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2-176

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2-177
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2-178
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2-179
Degradation is most rapid for the 0.81% Si-containing iron particles.

The sample containing 0,95% silicon is more resistant to degradation

until the relative humidity is above 59% at 708C. Finally, the sample

containing 1.12% silicon is the most resistant to degradation exhibiting almost the same rate of loss at 7% relative humidity as it does at

74% relative humidity.

There appears to be a threshold value of relative humidity that is

observed at the 0.95% silicon level and possible the 1.12% level, above

which the degradation rate increases very rapidly.

As silicon content increases, the critical humidity (the humidity where

rapld degradation occurs, at a given temperature) also increases. However, the degradation ceases at o s value of 50-60 EMU/gr for the 0.81%

silicon sample (Figure 2). The trend appears to be the same (a saturation limit) for the 0.95 and 1.12% Si particles also.

Interaction of Temperature, Humidit_ and Silicon. The three parameters of this study (temperature, percent relative humidity and percent

silicon content) interactively influence the degradation of the iron

particles. Thus, statistical analysis was performed to quantify the

contribution of each variable and present it in a manner that could be

easily visualized. The measured characteristic was the loglo of the

degradation rate in specific magnetic moment (EMU/gram-second 0"5) as

derived from the results of the experimental matrix.

2-180
The design predictor equation determined using XSTAT is as follows:

log10 (Rate) = -14.76 + 25.26(Xsi) + O.04176(XRH)

+ 0.0015(X T * XRH) - 0.05963(X_* XRH)

+ O.O00068(XT )2 - 12.49(Xsi )2

+ O.O00219(XRH)2

where:

X i : concentration of silicon in weight percent

X T = temperature in degrees Celsius

XRH = percent relative humidity

The percent variance explained (how well the regression equation predicts the data) was 96.03% so the model can be considered as quite

good. Solving the predictor equation via the computer produces two

dimensional contour plots of percent relative humidity versus temperature at constant silicon content. The values of constant degradation

rate were transferred to a psychrometric chart (Figures 5, 6 and 7) so

the relationships between absolute humidity (expressed as pounds of

water per pound of dry air), percent relative humidity and temperature

as a function of silicon content could be observed. The non-linear

degradation behavior becomes very obvious when presented in this

manner. A rate value can be taken from the contour plots for a given

temperature, humidity and percent silicon content and be used to determine how long it would take for the magnetic moment to degrade to some

predetermined value.

2-181
Figure 5.

DEGRADATION RkTE CONTOIJILSOF IRON POM)ER

.00

(0.81t SILICON)

o I

20 30 40 50 6'0

T_era1:ure,

70 80 90

Celmium

2-182
Figure 6.

DEGRADATION RATE CONTOURSOF XRON POWI)ER

(0.95t SILICON)

.50

| I

20 30 40 50 60 70 80 90

T_Lra_:uz'e, Cels£uJ

2-183
Figure 7.

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,,,.®,, , egF_/[/'l/ ;

,.£_'_//y,,4./.. !!/o.o, o

,.TIo.o_ t

| I J

20 30 40 50 60 70 80 90

Tezpera=ure, Celmlum p
For a constant absolute humidity (above the critical value, depending

on silicon content) increasing temperature will cause the degradation

rate to decrease. It appears that relative humidity is the controlling

factor. The corrosion rate appears proportional to the thickness of the

adsorbed water layer on the surface of the test specimens. The higher

the relative humidity, the thicker the adsorbed layer, hence the faster

the corrosion rate.

The behavior observed in the contour plots follows an expression of the

form Rate = Ae (b%RH)e-(Q/RT) , where at low humidity temperature is the

controlling factor, then a transition occurs where humidity effects

prevail. It is obvious that special precautions should be taken when

attempting to predict long term, low temperature behavior based on high

temperature data with a system that is humidity sensitive. Actual

archival stability could be less than expected unless humidity control

is considered. The value of statistical analysis to the interpretation

of oxidation behavior is clearly evident.

CONCLUSIONS

This study has shown the effects of percent silicon content, temperature and percent relative humidity on pre-passivated fine iron particles used for magnetic recording.

2-185
When the iron particles were exposed to various temperatures between 50

and 120°C at very low humidity it was observed that the degradation

rates were not affected by either the silicon content or the initial

value of the magnetic moment. TEM micrographs revealed that the oxide

layer grew thicker leading to a condition of passivity.

It was shown that for a given temperature there exists a critical relative humidity value above which the degradation rate of magnetic moment

increases markedly. The presence of silicon appears to increase the

critical humidity value at which rapid degradation occurs. When the

magnetic moment degrades to 50-60 EMU/gram it remains constant for

additional exposure time. _

A parametric expression has been proposed to relate silicon content,

temperature and humidity to the initial rate of specific magnetic

moment degradation for the iron particles used in this study.

2-186
Up here, if you increase temperature and maintain constant absolute humidity in the

air, the degradation rate actually slows down, which means you might make a prediction

conservatively that you might have better lifetime than you thought.

What these numbers correspond to is that they are EMUs per gram per root second of

degradation rate; and what I can really translate it to is that to sustain a 10 percent loss in the

EMUs per gram of the powder--the magnetic signal--this - 1 value corresponds to 3 minutes that

will lose 10 percent of its signal.

By the time we get down here to the .01 rate, 13.5 days to lose 10 percent; and then, the

next contour line, which would be down here, .001, which is a five-year rate. Five years under

more normal operating conditions based on data from much accelerated conditions. Five-year

lifetime for the particles to lose 10 percent of their signal.

Again, remember, if we get it into tape, there is an additional layer of shielding; put it in

a cassette, another layer.

What we are doing is proposing this methodology to do testing to really be able to do

empirically derived predictive testing for determining what is the lifetime of tape--what is

acceptable. How long will that rea/ly take? You have to be able to quantify what these rates

are--these rate constants--as a function of both temperature and humidity.

So, to summarize, our feeling is that metal particle media based on the data I have

shown you, both for environmental exposure conditions--we saw numbers onthe order of I to 2

percent over three years--some of this methodology here.

We feel that metal particles are a viable vehicle for high-density recording. They are

not as stable as the gamma iron oxides. They are not as stable as the chromium dioxide. But we

feel that, within acceptable limits, it is a viable vehicle and that, for whatever lifetime you

need before it's recopied to a new format or rerecorded, we think that the metal particles

themselves do provide a good means--an excellent means of recording at high densities.

I have also then shown you that the data must be collected and crunched to give true

archival predictions as to what the lifetime of the tapes will be. The manufacturers will be able

to substantiate their claims with this kind of data as to how long the tape will last.

Thank you.

(Applause)

DR. KRYDER: Okay. The second speaker from Ampex is John Corcoran. John Just

recently retired from Ampex, last March, but is now working as a consultant for them.

John spent 30 years in optical and magnetic recording. John will be talking on the

archival stability of metal particle tape. John?

_HIVAL _TAB_rrY QF METAL PA.aTICLE TAPE

Mr. John Corcoran

Consultant/Ampex Corporation

MR. CORCORAN: I think most of the other speakers all come from the tape

manufacturing community; I actually come from the recording community.

2-!87
Aboutfiveyearsago,SMPTE,agroupof 31 companies,representingbroadcasters,tape

manufacturers,and equipmentmanufacturers,startedto put togetherwhat is now referredto

asthe D-2standard.

Actually,it shouldbecalledtheproposedD-2standard;it takesforeverto getthese

things done.

Thequestionof tapestability wasa keyissuethen.

{Showingof viewgraphs)

MR CORCORAN:I happento haveherea paper,and I havecopiesof it ff anybodywants.

preparedby a chairmanofthe committee,RobertD. ThomasofABC. And oneof the key

conclusionsof thegroup at that time wasthat metalparticle tapewill besatisfactory"under

rigorousbroadcastconditionsand the useofbarium ferrite wouldnot bebeneficialbeforeat

least1990."

(Changeof viewgraph)

MR.CORCORAN: Now, four tape manufacturers report their earliest experimental

tapes--and Allan made one, and Darlene has made another; and Sony has separately reported

on this, and I believe Hitachi has--tapes that they made 12 or 13 years ago, all of which still

play back the original recording signals in an acceptable manner.

Three digital recorder manufacturers in the last year have reported that tapes protected

in the cassette wffi not degrade. Ampex presented a paper on this; Digital Equipment

Corporation has presented a paper on this. Dr. Speliotis was a co-author on that paper; he did

the magnetic work. And Exabyte has also looked at that.

The effect of the cassette on protecting the tape is much larger than is generally realized.

In spite of these facts, the question of stability of tapes is still with us; and I don't know how

long it is going to remain with us.

There is considerable evidence; I would like to point out, though, that tapes will survive

very well under what I will call archival conditions. Now, archival conditions do not include

continuous storage at high temperature and humidity.

There is a considerable number of papers that have been presented before--Bertram,

Cuddihy--on what happens if you try to do that. And it won't work with the metal particle tape,

and it won't work with iron particle cobalt gammaferric oxide tape either. (Change of

viewgraph)

= = _ ;

MR. CORCORAN: Here's a chart comp_ the uses of various types of tape and various

applications over the years. You will see that metal particle tape here has become more

common. The most recent one I_'e added here is a metal particle in a 3480 cartridge.

{Change of viewgraph}

MR. CORCORAN: in our stu_es, we have taken samples oftape from four different

manufacturers, all that were available last year: Ampex, Sony, Fuji, and Hitachi. And we ran

them in this Battelle environment, we measured the error rates of those tapes beforehand; we

measured them after.

What I have done here is plot the before versus after error rate measurements on three

or four cassettes of each of the four brands. Now, this data happens to be for what I call "nonburst errors," where you have isolated single errors. That does not necessarily mean random,

but they are isolated. They are not clumps.

22188
AMPEX

ERROR RATE MEASUREMENT

ALL ERROR DATA PRESENTED IS "RAW" TO PERMIT DETECTION OF

ANY CHANGE IN THE MEDIA. (WITH ERROR CORRECTION

APPLIED, MOST CASSETTES WOULD RUN ERROR-FREE, AND

CORROSION EFFECTS WOULD BE UNDETECTABLE).

SYMBOL (OR BYTE) ERROR RATE (SER) IS USED FOR D-2 DATA

BECAUSE THE REED-SOLOMON ERROR CODING IS SYMBOL

ORIENTED.

BURST AND NON-BURST ERROR DATA ARE PRESENTED. NONBURST DATA INDICATE ERRORS IN INDIVIDUAL BITS DUE TO LOSS

OF SNR, MEASLES, ETC. BURST ERRORS ARE PRIMARILY DUE TO

SURFACE DEFECTS.

POST TEST DATA ARE PLOTTED AS A FUNCTION OF PRE-TES ._ FGR

THE SAME CASSETTE. POINTS BELOW THE "NO CHANGE" LINE

INDICATE IMPROVEMENT.

Correlation of Non-Burst Error Rates Before and After Exposure Period

of D-2 Tapes From Four Manufacturers

./

• .£arp_,_C_

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2-189
AMPEX

\.

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2-190
The data generally shows the error rates are lower after exposure. The black dots

represent the exposed data; the clear dots represent controls. We kept controls with them.

They both go down, indicating probably our transport improved.

viewgraph)

(Change of

MR. CORCORAN: And we did the same thing with looking not at the isolated errors, but

at clumps of errors; and some of us feel that clumps are more likely to be produced by corrosion

than single ones. We get exactly the same effect. The tapes did not degrade.

(Change of viewgraph)

MR. CORCORAN: Now, I would like to mention barium ferrite. Barium ferrite is

considered to be one of the more stable materials that we can have. Unfortunately, we don't

have very much of it.

Ampex had one sample, which we have run on recorders; and we had trouble with

shedding. And this is not uncommon when we try a new tape on a recorder. It turns to dust, and

then we have to tell the chemist: Go back and fix up the formulation.

We would like to have other samples in the D-2 format. Some day it may prove to be an

interesting media; but at the present time, it Just isn't available. Thank you.

(Applause)

DR. KRYDER: Okay. Thank you, John. The final speaker this afternoon, before we

break into the discussion will be Dennis Speliotis. Dennis was born in Greece and obtained his

university education in the United States, receiving a Ph.D. in Solid State Physics in 1961. He

worked at IBM from 1961 to 1967 and became Manager of Recording Physics.

Dennis subsequently taught at the University of Minnesota from 1967 to 1971, where he

established the Magnetics Research Laboratory. He was a co-founder and vice president of

Microbit Corporation, where he worked on electron beam memories.

Since 1977, he has been President of Advanced Development Corporation in

Burlington, Massachusetts, doing consulting in advanced magnetic materials and magnetic

recording. He co-founded in 1984, and is President of, Digital Measurement Systems, Inc., also

located in Burlington, which manufactures advanced vibrating sample and torque

magnetometers.

Dennis will talk about corrosion and barium ferrite, and I'm sure he will give us some

comparisons to other media.

CORROSION AND _ IEERRII_

Dr. Dennis Speliotis

Advanced Development Corporation

DR. SPELIOTIS: Thank you, Mark. I have had two pieces of advice, one from the

chairman of our session and one from Dr. Hariharan. One was: Be very brief. And the other

one was: Be very nice. And interspersed between those two also was: Be controversial.

it.

This advice is rather conflicting, but I will try to satisfy all the suggestions if I can help

(Laughter)

2-191
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2-194
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2-196
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2-197
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2-199
DIFFUSION INTO REELS

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2-200
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2-201
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2-202
Conclusion_

o

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.

.

,

The archival life of four brands of D-2 tape have been shown to

exceed 14 years in the Battelle Class II environment. No

evidence of corrosion was found.

The cassette is a necessary element for achieving this life.

Dangling tape out of a cassette invites failure.

Extended exposure of any type of tape to high temperature and

humidity causes binder degradation and coating failure.

Archival storage is not possible in such environments.

An archival storage system includes: the tape, its cassette,

other protective enclosures (if used), the storage vault, and its

material parameters and the environment. Methods of

determining time constants and attenuation factors for

estimating storage life have been suggested.

There is a need for research -- perhaps here at the University

of Alabama -- to determine adsorption coefficients of tapes,

cassettes and other materials used in archival storage to use

in life predictions.

J

2-203
2-204
Dl_ SPELIOTIS: Well, we already heard about various kinds of tapes and their stability.

There is one important issue, however, that I would like to remind everybody; and that is, we

didn't hear very much about gammaferric oxide per se. Why? Primarily because the

performance of y-ferric oxide is not adequate to meet the demands of high density data storage.

So, really stability and archivability are important, but performance is also

important. We are talking about high performance media. We talk about terabytes of data;

some people even talk about petabytes of data, 1015 .

So, obviously, high density is very important. What we would really like to have is very

stable media that will also have high performance.

If we keep this in mind, I submit to you that most of today's highest usage media, such as

Co-dopted T-Fe203 and chromium dioxide are not extendable to very high densities. Therefore,

they will fall by the wayside in the future--no doubt about it.

Co-doped T-Fe203 is not extendable because if we add more Cobalt, the temperature

dependence of the coercivivity becomes excessive. This is a reversible change--not irreversible.

It is Just a reversible temperature change; coercivity drops as the temperature goes up.

Chromium dioxide is not extendable because we cannot go up in coercivity very much. There is

only one way that has been found to extend the coercivity of chromium dioxide to very high

values, which is required for high density storage, and that is to dope it with Iron; but the total

amount of Iron in the world would not be enough to satisfy even a minuscule percent of the

requirement.

Iron doping of chromium dioxide is another possibility, but that is limited. Maybe the

maximum coercivity that can be obtained is about 1,000 Oersted, which is not good enough.

So, I am going to scratch off the list for the future chromium dioxide and cobaltmodified iron oxide. That leaves metal particles and ME. Nobody has talked about ME, and I

will say a few words. Metal-evaporated tape is a very natural extension of the technology to go

to high density data storage. Why? Because we can get very high coercivity in metal particles

and very high magnetization at the same time, which is beautiful.

On ME, of course, we get high coercivity, very high magnetization, and thinness, which

is also very important to go to high density.

So, it is only logical that the Japanese and us, later adopted the use of metal particle and

are beginning to adopt ME for high density storage media.

Now, there is a new material; John said it is not available, but it is becoming available:

barium ferrite. Barium ferrite is a very stable material; Darlene did not mention it, but on her

chart of stability, there are only two materials that are really stable. And I don't think

anybody argues with this.

Plain T-Fe203 and barium ferrite. On Darlene's chart, those were the only ones that had

red dots, meaning stable under all conditions--no change. Okay.

Now, barium ferrite also is a material which allows you to attain any coercivity you

want--any-- including higher coercivities than metal particles. If you want 5,000 Oersteds, if

you can write on it, you can have it.

Now, there is one problem with barium ferrite; and that is that the magnetization is

relatively low, about 60 EMU per gram. However, as you saw, on many of the metal particles,

the magnetization is dropping and is dropping very rapidly. Pure alpha iron has a

magnetization of 210 EMU per gram; today's metal particle tapes use particles which because of

the oxide required to protect them, plus the silicon fortification--what is called armor

2-205
fortification--silicon alumina, ceramic fortffier- the effectivemagnetizationwith the

particlesis about half of that of a-Fe.

Now,with theseparticles that are used today in metal particle media, the size of the

particles typically is about 1,500 Angstroms in length and about 1/8th to 1/10th of that in

diameter.

They have a protective coating roughly on the order of 3 nanometers, about 30

Angstroms.

Now, let us make a simple calculation. If you take this particle and make it smaller,

and you must make it smaller because you cannot extend the high-density capacity of metal

particles without using smaller particles (the particles are already too large as they are today

for real high density). If you make it smaller, like 1,000 angstroms in length, and about 100

angstroms in diameter and have roughly not 30 angstroms of protective coating, but maybe 25,

you calculate the magnetization of that particle to be below that of barium ferrite.

So, metal particles are not extendable into the real h_h-density requirements of the

future. I can take the best metal particle tape that is available today, and compare it with

barium ferrite experimental tapes; the barium ferrite, in spite of its low magnetization,

outperforms the metal particle tape in absolute signal--not in noise--it outperforms it in noise

at much lower density--but in absolute signal, for any density over 75 Kfci.

At densities above 75 Kfci the barium ferrite tape has higher absolute signal than metal

particle tapes. The reasons for this are beyond the scope of thisconference; there are certain

fundamental demagnetization processes that are very different in the casegf barium ferrite

than in the case 0f metaIparticles. _ _

Now, many of us have also heard--and I think I should say a few words--about ME tape--

the metal-evaporated tape that in some quintets is supposedly going to be the ultimate

successor of all of these tapes. It is going to be the high-density, high-deflnition media of the

future. And the question is: How, for example, does barium ferrite tape compare with ME tape

recording-wise? The performance is identical within half a dB at anything above 130 Kfci.

So, if you really want to talk about high density, I think the real possible contenders are

barium ferrite and ME tape. MP tape is not extendable.

Now, let's go to the subject of our seminar here, which is called instability. There are

some very important issues; Allan made a very important distinction between long-term

archivabflity versus environmental stability. It is obviously a complex issue.

What I will show you are some error rates that were measured using a Media Logic ML4500 tape tester, which uses an Exabyte drive. The measurements were done on 8 millimeter

metal particle, ME, and some experimental barium ferrite tapes, all of them 8 millimeter. We

did immediately read after write.

These tapes were e_posed to a corrosion test which was only temperature/humldity; 7.5

weeks, at 50°C/80% relative humidity,

When I put the tapes in the chamber, they did not have the protective plastic box; I Just

put the cassette in, the way you mount it on a recorder, simply because I didn't want to be

limited by diffusion effects, if any, in that period of time.

(Showing of viewgraphs)

DR. SPELIOTIS: Here are some typical results and error maps, before and after

corrosion, for 40,000 tracks, on the Exabyte drive. These are not single bit errors; the machine

2-206
Corrosion Test: 7.5 Weeks 50C, 80% RH

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2-207

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2-210
can certainly count single bit errors, but they are larger errors because the data correction in

the Exabyte drive can handle blocks of erro.rs.

In any case, there was a very large increase in error rates in the MP tapes.

(Change of viewgraph)

DR. SPELIOTIS: ME tape has a much higher signal- to-noise ratio than MP; and when

you look at it before corrosion, it is very clean. So, there is nothing to show before; there are

hardly any errors.

But there is a lot of difference between different ME tapes; and I'll show two of them,

both of them after corrosion, for manufacturer A and manufacturer B. There are relatively a

lot of errors, a much larger increase percent-wise than on MP tape.

And there are many, many errors at the front part of the tape on which I had done a lot

of testing for short blocks; and the rest of the tape, I hadn't looked at, but there was some

corrosion.

There is clearly some diffusion limitation; there is edge corrosion. This is one edge of

the tape; this is the other edge. And this is down track. And there is some significant edge

corrosion limited by diffusion apparently and a tremendous difference between

manufacturers.

(Change of viewgraph)

DR. SPELIOTIS: Of course, the same thing applies to MP tape. There is a very big

difference between the unfortified armor protected particles and the plain oxide protected

particles.

(Change of viewgraph)

DR. SPELIOTIS: Here is a metal particle tape, again with excessive testing on the front:

once every day for 20 minutes and then it was put back into its cassette enclosure (this was not

exposed to an accelerated corrosion test but was in my office for one month).

The tape developed a pretty large number of errors in one month. In the beginning, this

was very clean; when I opened the cassette from its plastic sealed case, it was very clean. It was

Just sitting in the office which is typical of most offices.

DR. SPELIOTIS: Here is a barium ferrite tape measured similarly to the MP tape--no

effect. So, magnetically and error-wise--and of course, the extent of the errors is the real

criterion, I think-- there is a very significant difference for these tapes, even in a normal office

environment, without doing any accelerated corrosion testing.

Now, to summarize: Is there a disagreement between what the other speakers said and

what I have said? I don't believe there is any disagreement at all. Let me state the view as I

perceive it including the tests that John Corcoran referred to: the published data, a very

extensive study by many people over many months--that was done on behalf of Digital

Equipment Corporation.

This is going to be published this August in the Journal of the Electrochemical Society,*

and it is a study of the stability of MP tapes.

* JElectrochem. Soc., 138 (1991) 2504-2509

2-211
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2-219
What we found was: If you take these tapes inside the cassettes and expose them to a

Battelle environment, which is a very moderate temperature/humidity but with polluting

gases present, there is some increase in errors, but no problem at all.

Our opinion _at-the cassette protects _e_pes primarily because there is not enough

chlorine, including diffusion, but even ff there were diffusion, there is not enough chlorine to

really get in and do the damage. Now, ff we expose prerecorded tapes to a Battelle test outside

that protected case, (open tape with data) all the tapes, including ceramic protected, were

destroyed; after seven days they were unreadable.

And then, Her rewriting them, they were unreadable--all gone(

- , , "7 Y ....

Now, the same test on prerecorded tapes inside their cassettes, exposed to a

temperature/humidity test for anywhere from 10 days to 70 days.We found that after 30 days

or 40 days, there was some increase in error rates, but not a very big problem.

After 70 days, most of the tapeshad data that was unrecoverable, on a

temperature/humi_ dity test, inside the cassettes.

We interpret this to mean that there iS plenty of humidity around and is doing a Job on

these tapes. On the Battelle test, the humidity is very low--relatively--and the temperature is

moderate; and there is not enough chlorine, which is presumably the primary culprit to

damage the tapes.

I don't think these findings are in disagreement with what other people presented; but if

there are some opposite opinions, they should come out at the following discussion.

One very wo_ome thing about the metalp_cle tapes that were studied at DEC was

that on the Battelle test, we kept taking the tapes out of the chamber every couple of days to

determine what was the change in error rates.

This particular Battelle test was a 12-day test, and we took the prerecorded tapes and

measured the change in error rates every two days. Normally what you would expect to happen

due to corrosion would be that you would have initially some rapid corrosion because of

surface effects, and then, it would level off because the corroded surface would become an

inhibitor for further corrosion. What we found was exactly the opposite.

For several days 0f _0sure, corresponding to years of projected life, not much change;

and then an exponential, dramatic increase in error rates near the end of the test. This really

needs to be tried over again and understood.

If it is true, it could mean that we are sitting on a time bomb. It would have these tapes

looking fairly stable and fairly good; but after some time, they would fall apart. Thank you.

(Applause)

DR. KRYDER: Could I get all the panel members to come forward, please? I will ask

them to sit in the order that they spoke, but leave some extra space for Mike Younker. Mike is

an interpreter here for Sony.

(Pause)

DR. KRYDER: I invite questions from the audience to get us started. Go ahead.

PARTICIPANT: Yes. 18 months from now, I will have to start shipping a system with

high density tape. What tape should I plan to use? (Inaudible)

DR. SPELIOTIS: You know my answer.

2-220
DR.KRYDER:Wen,whatis youranswer?Hehasgotto ship it in 18months.

DR. SPELIOTIS:18months? I think it will. Barium ferritetapewill beavailablein

adequatesupplydefinitely in 18months.

PARTICIPANI2.But it hasto betested.

DR.SPELIO'I2S:Right. Youhaveto testit; so,it has to beavailablemuch earlierthan

that.

PARTICIPAN'E. Therearenowfivecompaniesthat haveD-2 tape. Youwill now have

your optionto lookat varioussources.I don'tthink thereis anyhopethat that is goingto be

available-- (Inaudible}

DR.KRYDEI_ Could I ask the people to pass the microphone around for those who are

speaking?

PARTICIPANT: 8 millimeter, 4 millimeter -- (Inaudible)

{Inaudible discussion}

DR. KRYDER: John, can you repeat the question?

PARTICIPANT: {Inaudible)

MR. CORCORAN: For instance, the other questions like: Do you want it all in one

cassette? Do you want many cassettes to a lot of different people? What data rate do you want?

PARTICIPANT: {Inaudible)

MR. CORCORAN: Okay. Now, you can do that in four small D-2's or two big D-2's. If you

do it in Exabyte, they are about 2 or 5 glgabytes, depending on which one. So, you could do that

with 2O.

PARTICIPANT: (Inaudible}

MR. CORCORAN: Right. Now, what data rates do you want them to read at?

PARTICIPANT: (Inaudible)

MR. CORCORAN: I think if you will use the metal particle tape, under the "normal

commercial practice" and you don't expose it to high humidity for an extended period of time,

you will not have any trouble with it.

DR. SPELIOTIS: But you cannot guarantee this for shipment.

MR. CORCORAN: The tapes that we used and I showed data on were shipped back and

forth, from Redwood City to Battelle and back.

PARTICIPANT: With the 85 degree temperatures, I could easily achieve those --

(Inaudible) -- if they were sitting out on an aircraft tarmac --

MR. CORCORAN: Well, I'd be a little surprised if you got 85 ° Celsius on a tarmac. I know

it will get up to 55 or 60, but not 85.

2-221
DR REAG01_Thetentativerecommendationwearehavingwith regardto chromium

dioxideand metalparticle is that youarein variouszonesof safety.You areverysafeif you are

between30and50%RH andlessthan 50° C.

If yougobeyondthal, youaregoinginto azone ofmore risk. If you get up to 70-80% RH

for any extended period of time, you are taking a risk. _

Now, we are talking about several different risks, not only pigment, but we are also

talking about changes in the hydrolysis of the binder and also in the stability of the polyester.

So, again, what we are talking about is the degree of risk that you want to take as you are

implementing these types of sYstems.

DR. KRYDER: A question in the back?

PARTICIPANT: (Inaudible)

MR. HADAD: What kind of problems?

PARTICIPANT: (Inaudible)

MS. CARLSON: There are probably two different mechanisms that could occur;, and

therefore, it is very difficult for us to make a recommendation without knowing what the

mechanism of failure is. But there are probably two different mechanisms.

One: Remember the slide I talked to you about -- flit was sitting for a long period of time

in a hot and humid environment, you could get outside of the track, could get outside of the

format that the recorder could play back. Or else, you could have-signal degradation.

Now, unless we see what you actually have, it is very hard to know what

implementation procedures we would recommend; but we can talk about it. There are two

obvious mechanisms that can be going on.

MI_ HADAD: Yes. I would say it would be more of a physical phenomenon, the --

changing, which is common to all tapes, as opposed to a magnetic change. I showed the data, of

course, where we get the magnetics; and in periods of up to six months in those high

temperature/humldity conditions, there would only be a loss in magnetization of I or 2

percent.

PARTICIPANT: (Inaudible)

MR. HADAD: But again, you said some of those tapes had been shipped from some long

distance; and that was the result of receiving it from Germany?

PARTICIPANT: Yes. (Inaudible)

MR. HADAD: Okay.

DR. KRYDER: Another question?

PARTICIPANT: (Inaudible)

(Inaudible discussion)

DR. KRYDER: Speak up, please.

PARTICIPANT: (Inaudible)

E

2-222
MR.HADAD:It would beawfuUydifficult to monitor. Foreignmatter gettingon them

is very randomized; and I think it would be very difficult to model that. So, the idea would be

Just to keep the tapes in as clean an environment as possible, although we recognize that --

MR. CORCORAN: It would show an error rate like I showed. If you are getting additional

dirt, the error rate is going to degrade.

PARTICIPANT: I would think it would be a higher random error rate.

IVIR.CORCORAN: Yes.

PARTICIPANT: (Inaudible)

MR. CORCORAN: We did not see it. Okay? Now, there is undoubtedly some condition

you might find it in, but we did not find it in the Battelle test.

DR. HADAD: That would be independent of format, of course.

DR. REAGOI_ Let me go into that. From a user's standpoint in tape storage, we do the

analysis of the particulate impact; and we can actually predict particulate deposition rates

onto surfaces.

From the models we have used and from actual examination of the tape storage areas of

particular environment, particulate contamination contributing to future degradation is not

an issue.

The shielding from the containers is so high that the actual deposition velocity, since

there is no movement in the cartridge, there is no impetus to pull particles from the

environment in, as their natural grounding movement brings a very small amount Just to the

openings that are exposed.

The biggest concern we have had with the magnetic tapes, in particular the 3480s, are

localized contaminants from the people that operate the systems.

And we have been able to show that, even in the

cleanest of a data center, the localized input of a person walking up and removing a cartridge

and putting the nextone in, it is the dirt on that person that leads to the problem and the

failure. And we can actually tell you the color of their hair and who used it last and things of

that nature.

(Laughter)

DR. REAGOI_ And that is the issue that we have started to address in terms of the air

flow dynamics in the data center around a tape reader and the fact that you have to change it in

order not to strip off the dirt of a person--and these are things we are not actually looking at--

and actually have it come up in the air and flow inside the tape reader at the point of change.

DR. KRYDER: Another question?

PARTICIPANT: (Inaudible)

MS. CARLSON: I think that the point that Dennis made earlier was that for systems

that used 2000 fci or 1600 fci--you know, nlne-track tape--you should stay with nine-track tape

because that is a very stable environment. However, you cannot get up to 45 Kfci or 100 Kfci; you

Just cannot get the performance from the 9-track tape system

PARTICIPANT: (Inaudible)

2-223
DR.KRYDER:LetmeJustbriefly summarizethat. I wasaskedto repeatthe question.

The second one was: Is there an effect of horizontal versus vertical storage basically on the

tape? Go ahead, John.

MR. CORCORAN: I think in general the rule still is that you should store the reels with

the axis horizontal. Now, we tend to have smaller cassettes today; I think perhaps the problem

is less intense than when we had big 12 and 14 inch reels. But you will still do better ffyou keep

them horizontal.

PARTICIPANT: Why? {Inaudible)

MR. CORCORAN: You don't have slippage of the reel packs.

PARTICIPANT: (Inaudible}

MR. CORCORAN: The smaller cassettes do have less tape on them. If the ratio of O.D. to

I.D. exceeds 3, cinching can occur regardless of how large or small the tape is.

PARTICIPANT: {Inaudible)

MS. CARLSON: First of all, I would always recommend rewinding to the beginning of

tape or to the end of the tape, specifically because polyester does deform; and ff you have it

exposed, you are going to get crease marks or deformations on any of the bending radii that you

are storing it on.

So, in archives, that is one of the things that was mentioned early today. Some of the

systems unload, but dont rewind the tapes. That's fine as long as you are not having those tapes

stay in that condition for more than three months.

After three months, you should really have it stored at beginning of tape or end of tape

because you will lose data at those crease marks.

DR. KRYDE_ What was the first question? I'm sorry; I missed it.

PARTICIPANT: {Inaudible)

DR. KRYDER: Don't you really mean: How realistic are their tests and the

extrapolations from those?

MR. HADAD: Personally, I feel the temperature/humidity are the major issues. And in

terms of smoke or ozone, no, we have not addressed those. Looking at it Just as a background

level, leaving it constant, and then we are more concemed in our own modeling. And again,

those models that i showed were only the particles; we haven't gotten to the tape yet. That's

proposed.

But all of that other was sort of background; and we felt the temperature/humidity was

the most critical.

DR. KRYDER: Dennis, do you agree with that?

DR. SPELIOTIS: Yes, I think temperature/humidity is the most damaging. I believe the

gases are not so severe; there are not so much of them around. For metal particles, there is a lot

of iron in a D-2 cassette, a lot of iron and there is not enough chlorine to affect it.

PARTICIPANT: (Inaudible)

2-224
MS.CARLSON:It's 45. That'scobalt-doped;that's not iron oxide. {Inaudible

discussion)

MR. HADAD: It's a cobalt modified --

MS. CARLSON: Yes.

MR HADAD: Cobalt modified T-Fe203.

(Inaudible discussion)

MS. CARI_ON: Yes. Co-doped T-Fe203 is a fairly stable material. The only problem

that you have is at high temperature and humidities, the cobalt will diffuse into the T-Fe203;

and therefore, you lose coercivity.

And in a normal controlled environment, that is very good. However, the point that

Dennis made is that at about 50 KFCI, cobalt-doped is as high as you are going to be able to get

with cobalt-doped material.

PARTICIPANT: (Inaudible)

DR. REAGOR: From our standpoint in the Bell system--the Bell Companies--we went

from the open reel iron oxide tapes to the chromium dioxide tapes, not because of looking for

better quality materials; it reduced the size of our storage by about 80 percent. We could put the

same amount of information, and now that bulk to protect our things for archiving is a lot

smaller. And so, when we went to that mode, it was not because--and I think you have been

hearing this--it is not done because the material may be that much better; it is because it is

giving the end user a better storage capacity per inch.

And depending on what that end user needs and what those requirements are for

archiving and how much data they project they are going to have, that may govern what you

want and what you are going to use in the future.

But in terms of my area, it was strictly space. We were running out of space to keep the

tapes; and you know, it costs money to maintain that space.

PARTICIPANT: (Inaudible)

DR. KRYDER: Another question?

MR. CROSBY: I'm Jim Crosby, and I would like to make a comment about -- (Inaudible)

DR. KRYDER: That's cobalt damage.

MR. CROSBY: As a matter of fact, it has a coercivity of 600 -- (Inaudible)

DR. KRYDER: No, it's cobalt.

DR. REAGOR: Okay.

DR. KRYDER: All right. We had a question over here and then another.

PARTICIPANT: (Inaudible)

DR. KRYDER: Let me briefly repeat the question. Let me paraphrase the question: He's

pointing out that it is not unusual in some parts of the world, particularly in Washington, D.C.

for instance yesterday -- (Laughter)

2-225
DR.KRYDER:To sit at 85 or 90°/6relativehumidityfor dayson end. And howdothese

testsrelate to that sort of an environment?

MR.HADAD:Thedatahas shownthe lowesttemperatureonthat was50° C; that is still

considerablyabovethat, but wedon'thaveworldwidedatayet from, say,shippingtapesover

thereand letting them sit in that environmentand correlating it back to our environmental

chamber being at those types of temperatures. But what we are doing with _the experimental

matrix iS coming down to what I would call the lower temperatures, which are more in line

with those kinds of locations in the world. And eventually, we will have to develop that kind of

correlation.

=

Right now, we are Just using it to fit the model. We will establish a series of conditions

where enough change can be observed in a short enough time to build a model and then

extrapolate it further.

I know you run into danger when you extrapolate outside your experimental region; you

always run into a danger as to how good the model fits once you have left your original

boundaries. But this is something that is going to take some time obviously; it is Just sort of in

the process now.

DR. KRYDER: Dennis?

DR. SPELIOTIS: By the way, making a model on the basis of magnetic data can be very

deceiving because most people measure the entire change of magnetic moment of a piece of

material; and typically, the coating thickness is about 3 micrometers. That does not matter at

all in recording.

At high density recording, it is only the top .2 or .3 micrometers that has anything to do

with the signal that you read out of the tape. Therefore, you must measure of the change in

surface magnetization, "and not in the average bulk magnetization.

We did some such measurements and found that for all the tapes regardless of whether

they were double protected with ceramic coating or just the oxide, roughly, the average surface

magnetization change was three times greater than the total magnetization change.

If you take this three-time multiplier for the loss in magnetization, you will find out

that you are in trouble under some conditions. So. you must look only at the surface and not

inside.

In that respect perhaps, the error rate change is the most realistic measurement, except

that error rates aree composites. You cannot blame the particles alone; it could be the

particles, or it could be the binder; or, it could be the surface; or it could be any combination of

the above, and you have to sort of separate the effects.

DR. KRYDER: Okay. Another question?

PARTICIPANT: Somebody earlier said that there was really a difference between

archival and environmental. And most of what has been talked about really strikes me as

being environmental -- (Inaudible)

DR. KRYDER: Right.

PARTICIPANT: If you protect the tape against these things, aren't there any archival

problems? Will it be here 100 years from now? Will it {Inaudible}

DR. KRYDER. Okay. Let me repeat the question. The question was: We have been having

a lot of comments about having tapes in the typical environments--shipping to Saudl Arabia

2-226
and soforth; and what if they areproperlystoredin the "archivalenvironment"? Howlong

will thesevarious tapesreally last?

MS.CARLSON:MaybeI can addressthat. Thebottomline of that is recorder

obsolescence.

Historically,in the last 20 years,theweakestlink in the chainhas beeneither binder

hydrolysisor recorderobsolescence.That's thebalancingact that hasbeengoingon.

Binder hydrolysis--thechemistriesthat havebeencomingonboard havereally

improvedalot. So,the biggestquestionis: What isyour recorderobsolescenceoryour recorder

half-life?

MR.HADAD:Yes. Onething that Patsaidis that it wouldbearoundforever;but then,I

sortofwrotedownthenextthinghesaid."Makesuremewill be around long enough to make

the copy."

(Laughter)

MR. CORCORAN: Could I give you a criterion? The earliest video recorder made at

Ampex in about 1955 was a quad recorder. Those things were used in the studios until

somewhere around 1975. They have since disappeared into museums; there are a few places

you can find them.

They had these little glass things in them called vacuum tubes. You can't Fund the

replacement parts.

Somebody gave a talk about "IBM and finding the replacement parts on that; and that

was built from 1968 to 1972. That will give you a kind of rough criterion as to what the typical

life of these systems are.

DR. KRYDER. They are probably going to get shorter, though, I would argue. Technology

tends to change faster.

PARTICIPANT: There are ways around that. There is the obsolescence of chips, and

people now make -- chips that they can put -- (Inaudible)

DR. SPELIOTIS: 7-Fe203. (Inaudible discussion)

DR. KRYDER: I guess another comment could be made. I mean, if you are willing to

spend the money, the tapes still exist. Even if the drive doesn't exist, we could undoubtedly

recover it; but you have got to pay for the development of that drive again.

PARTICIPANT: (Inaudible)

DR. KRYDEI_ We have a question down here?

PARTICIPANT: (Inaudible)

DR. SPELIOTIS: Seven and a half weeks was the test.

PARTICIPANT: Okay. (Inaudible)

DR. SPELIOTIS: There have been some correlations. This was an accelerated test; 50 °

C/80% relative humidity. This is not a standard operating environment. The correlations

show that seven and a half weeks correspond to seven years in real life; those correlations have

been done by other laboratories.

2-227
DR.KRYDER:Aquestionin the far comer?

PARTICIPANT:(Inaudible)

(Inaudiblediscussion)

MS.CARLSON:Youmustbein asituationwherebudgetsaren'tofconcern;but boy,in

the lastfiveyears,wehavehadto domorewith less.

PARTiC/PANTi(inaudible)

DR.KRYDER: Okay. We have another question?

PARTICIPANT: What's the wicked truth about -- (Inaudible)

(Laughter)

MS. CARLSON: In some conditions, yes.

DR. SPELIOTIS: The problem is much worse obviously with 4 millimeter than with 8

millimeter. I would think the reliability of 8 millimeter is much better than 4 millimeter. 4

millimeter is probably a real problem spot.

The other question is about the corrosion stability of these tapes. If you keep them in a

real archival environment; low temperature, humidity, there is no problem. But 8 millimeter

is now finding its way as backup storage for many small computer systems--home computers,

office computers, _:

Those tapes are going to be trouble. (Inaudible)

So, it depends on what environment and how you use it.

PARTICIPANT: (Inaudible)

DR. KRYDER: Can he expect a problem in that environment?

MS. CARLSON: Yes. Normal tape packs--and I think Dr Bharat Bhushan has done a

little bit of this tape pack analysis, where what happens is that you do get stress relaxation in

the tape pack; and therefore, you have a differential in tension. And so, that is the reason why

you recommend retensioning.

Unfortunately, with 8 millimeter, I don't know when and how much at this particular

moment in time; but you will have to retension most cassettes.

PARTICIPANT:

MS. CARLSON:

(Inaudible)

Retension Once a year.

MR. HADAD: Once a year is what we recommend.

PARTICIPANT: (Inaudible)

DR. REAGOR: One of the Other things that we noticed _so in our studies, and all studies

we did on the tapes was on virgin tape, it turns out when you manufacture the tape, it was

slress-induced during the manufacture and the initial first run; and actually if you take it

through one low temperature cycle, you can actually remove that initial stress that sometimes

later relaxes when you are using it.

2-228
PARq]CIPAN_.(Inaudible)

DR.RF_.AGOR: Yes.

DR.KRYDER:Otherquestions?

PARTICIPANq2. OneIssuethat wehavecomeacrossis howwegot startedin this entire

discussion;and that Is,wewantedto °° (Inaudible)--

DR.SPELIOTIS:On typicalMPtapesin themarket,asmuch astwoordersof magnitude

differencein error ratesunder someconditionsfrom onetapeto another,the bestto the worst.

DR.KRYDER: A question?

PARTICIPANT: {Inaudible)

DR- KRYDER: Yes. So, ! guess to sum the last two comments, there are variations from

vendor to vendor; and there are also variations even within one good vendor that are

significant.

PARTICIPANT: (Inaudible)

DR. KRYDER: Okay.

PARTICIPANT: {Inaudible)

DR. SPELIOTIS: For a long time, from the beginning of our modem era until five or six

or seven years ago, most of the data was stored on plain gamma--no chromium, no metal,

nothing--and gamma is stable.

So, I think that Is one of the main reasons we have not lost the data. Now, we are

moving into new media, and these are not as stable as the old ones; they are not.

MR. HADAD: The data I presented, again, under ambient conditions, it is routinely

maybe a dB change after three years. I think that is pretty stable. I don't know that there is

that much reason to be concerned with those kinds of numbers. I imagine there are 2 percent

changes in some cases, exposed to 30 ° C/70% relative humidity. Again. maybe we are getting

too excited, or we see the curves of the downward slope; but yet, we ought to rescale the axis.

With a 0 to 100°6 loss, our line Is way up here, of course we know with our Lotus and

Excel spreadsheets that we can take just a little bit of that and blow it up; and it looks like the

curve goes straight down. So, three-year data, 1%, somewhere around there.

PAR_CIPANT: (Inaudible)

(Inaudible discussion)

MR. HADAD: Yes, it is much worse there. Now, you are starting to exceed the material.

You know, basic material properties, at 85 ° C, you have pushed the glass transition point of

the base back.

At the moment, we can't do anything about that; you Just can't recommend tape to be in

that environment. You can't recommend something that will be that high.

MS. CARLSON: The point that I would like to make on that Is that's the reason why

archive systems are system-specific. In that particular case, there are workarounds. If you are

in a situation where you are at high temperature and humidity, what you would do is you would

2-229
identifythosetapesand then copythemoverontoan archivalmedia.

beusedin anarchiveway if it's implementedproperly.

All of thesesystemscan

Is thereany reasonwhy that high temperature and humidity tape has to be kept

forever?

PARTICIPANT: No, I think the issue is that _- (Inaudible)

_ CORCORAN: Let me comment. We have a number of DcRsi recorders out there in

that desert. And I heard no trouble about the tapes. In fact, the one complaint we got was that

they kept reusing them, and they never bought any more.

(Laughter) _ : :

MR_ CORCORAN! Now, theywere rerecording them almost _ery nightand then : _

rerunning them. But I'm pretty sure they didn't go through the glass transition temperatul_, or:

I don't think they would have got any data. :

PARTICIPANT: (Inaudible)

MI_ CORCORAN: I fiear what youare saying, but I think what you have to do is

distinguish between this "archival condition," when you are trying to go for long life, and the

extreme environment for maybe a week.

And it is routine, for instance in electronic news gathering cameras, to have trouble

with humidity and so forth on site. But that doesn't generally destroy an archival; it will muck

it up in a week, though.

DI_ REAGOI_ And in your case, what you are trying to do is sending a package data _

system -- .......

To be honest with you, from a user's standpoint, I would look at it as: What I send is

dependent upon what the person who is going to receive it can do with it. So, that format and

the type and the volume is going to be based on who you are sending it to.

And the real key is the transportation issue and the protection. No matter what

material you are hearing right now, the key seems to be that we don't leave it sitting on the dock

in the hot sun on a humid day, unless it is in some type of a profectlve container,

And I think the issue you are raising, that is: I had to call them and say "Hey, guys, don't

leave this in the back seat of your car four days before you read the tape." This is really the

thing that you are going to have to do.

DI% KRYDER: Did you have a question?

PARTICIPANT: (Inaudible)

DI% KRYDEI_ I'll repeat the question. If we wait two years for barium ferrite to be

developed, do we have the perfect medium; or are there some down sides to thai?

DR. SPELIOTIS: Let me say one thing about :that. The Japanese industry has already

developed barium ferrite as a copy tape for DAT audio. In other words, they record on metal

particle masters, classical music, for example, and for multiple distribution, they copy by

anhysteretic transfer onto Barium ferrite tapes. :_:

They are not marketing them yet; I don't know why. but they have been developed.

DI_ KRYDEI_ But that is not his question. The question: What is the down side to it?

2-230
MR.HADAD:Thechemistriesareprobablygoingto bevery similar to the binder

system. Still, wehaven'tgottenentirelyaroundall the environmentalproblemswith the

polyesterurethanesthat everybodyis using. Theyaresubjectto hydrolysis,mobilelubricants-

-all the things that weneedalsohadsome°- to it; andthey areprobablygoingto bepresentin

the nexttwoyears.

DR.KRYDEI_CouldI getthe panelto agreethat if theworlddoesgobariumferrite,the

stuffwouldbeasstableasgammawas?

DR.SPELIOTIS:Absolutely-- nochange.

MS.CARLSON:Barbarabringsup a point,andit dependsupon-- Barium is toxic;it is a

heavymetal;it is atoxicmetal. Andit dependsuponthe pigment-- if that material is goingto

bea toxicwasteissue. In the researchthat wehavedone,wehaveseenawidevarietyof

experimentalproductsthat couldbetoxic.Thedesignengineershavemodifiedit soit won'tbe.

I amanticipatingthat, by the time it is onthe market,bariumwill not bea toxicwasteissue.

DR REAGOR.As auser,I can address this. If there is a toxic question concerning any of

the materials, from a large user's stance, that is something we would not want to get involved in

To give you an example of that right now, the EPA is Just about ready to make telephone

poles toxic waste.

(Laughter)

DR. RF_,AGOR. That would cost my own company about $500 million a year from now on

if that happens. So, we are doing a lot of work right now on telephone poles.

MR. CORCORAN: Could I make one other point about °- From a system viewpoint, it

has a drawback on low frequency signals. (Inaudible) -- where we have to put in things llke

audio and control signals. The barium ferrite is not very good at that. It works great at the

high frequencies, but not in high syncopation °-

DR. SPELIOTIS: But John, all high density future systems, including DAT, digital

video, etc., are going to be PCM or band-llmited digital.

MR. CORCORAN: We have to build a whole new family of recorders to do that.

PARTICIPANT: (Inaudible)

CORCORAN: Wen, this will be another family. (Laughter)

DR. KRYDER: A question over here?

PARTICIPANT: Is that the ordy down side for the °° (Inaudible)

MR. CORCORAN: Every time we tried changing the tape--and I do this routlnely--trying

to bring in some new tapes and try them on the machines, we encounter another problem. And

then, we have to find a way to resolve that. Now, for instance, this could be solved by changing

the control track electronics. But these are the kinds of things that you stumble through as you

try to move forward.

MR. HADAD: It's not a direct swap out to any existing -- right now.

2-231
MR.CORCORAN:Yes,but the downsideis that it's hardto predictwhat theyaregoingto

beuntil youactuallygetit onthemachineandtry it.

DR KRYDEI_Anytlmeyouchangepart ofa recordingsystem,you haveto changeother

parts--that's my experience.

(Laughter)

DR.REAGOR:Earlier,you hadreferredto the metalevaporatedtapeashavingsort of

like this linear corrosionand then, all of a sudden,it went exponential.Andyou said it was

oppositefrom what you expected.

DR.SPELIOTIS:ThiswasonMP,and notMEtapes.

DR.REAGOR:But from theworkwehavedoneonmetalsurfaces,that iswhat youwould

expect.

DR.SPELIOTIS:Yes?

DR.REAGOR:Whenyouaredoinggasphasecorrosionof ametal surface,whetherit is

particlesizeor whetherit is a full layer,and youstorethat with a verysmooth,clean surface,

then you have to basically have an initiation period for what they call "mound formation";

that's the corrosion term.

And so, you have to start to develop a spot that finally starts to corrode, and that

initiation period can be very long. And then those mounds finally grow together. I noticed on

your data published, you almost look like in the early stages that you have clusters of

corrosion, which would be exactly what you would expect in mound corrosion of a clean metal

surface.

So, what we are seeing here is--and I don't want to scare anyone, because I don't think it

is going to accelerate aRer ten years and finally fall off the edge-- but I think it tells us that the

metal particles and the metal surfaces are behaving like the metals do. And so, you can now

extrapolate even a little further and look at these metal systems and say: Okay, what are the

corrosion dynamics of these materials in the real world?

_ --4

And then, you can go to a Battelle test that does copper surfaces; and ff the copper metal

surface behaves in this way and is accelerated this way, it is applicable to a metal particle

surface or to a metal evaporated tape surface; and so, there is some correlation here.

And what you were saying and describing basically fits into that whole field.

DR. SPELIOTIS: By the way, the corrosion of chromium dioxide and cobalt-modified

iron oxide, as far as I can Understdnd, does not involve any significant change in the volume of

the particle. There are other mechanisms, like the diffusion of the cobalt that lowers the

coercivity in the case of cobalt modified. But in the case of metal particles, the particle grows

very significantly in size when it oxidizes--20 or 30 percent growth.

Now, what is going to happen? It's going to distort the surface; it is going to do some

damage -- and it's a different mechanism of corrosion.

MR. HADAD: I think that some of those charts that I showed, though, that under

normal operating conditions, you are not going to get that kind of corrosion. I want to mention

something regarding metal particles starting off as a clean surface; they are not. There is a

passive layer. They already are corroded t0 some degree.

Passivity, Just by definition, is an oxide layer that protects further inside the core. And

so, I don't know; Ik,e never observed it with metal particle tapes where there is some long

2-232
induction periodandthen theytakeoff. Theyalreadycomepretty corroded,asDennissaid;

the EMUspergramof pureiron is 210. Thematerialyouusefor makingmagnetictapeis 115or

SO.

They are precorroded, but they give the outward appearance that people are interested

in. The sheer fact alone that that oxide is present is actually protecting further those particles.

They have already started corroding and stopped.

Of course, their passivation kinetics determine how long these things are going to last;

and what we see is that they are going to last many, many years. Of course, the process will

continue; but it is way beyond, I'm sure, our lifetime or our expectations of the media.

DR. KRYDER: A question down here?

MR. ROBINSON: Since I've been invited to make a presentation on tape recording, I

thought I might say a word or two. I doubt that the coercivity change of the tape will make a

difference, you know, going from Germany to here.

If I were you, i would do what I've done in the lab many times, trying to test machines: I

would check my tracking.

(Inaudible discussion)

MR. ROBINSON: Let me Just say another word. If I were using metal particle tape, I

think I would clean the heads also because of brownstaining. Exabyte, I think, recommends

once a day. (Inaudible) So, I would be very concerned about that.

I would also be concerned about using 8 millimeter without my track -- If you recall my

presentation, the ID-1 Working Group, including Sony, DataTape, Ampex, and others, selected

a 1.6 mm And we also said, in answer to many, as was reported, that we would make our track

as powerful as possible.

I believe we need some advice from manufacturers --from you folks--about whether we

are doing the wrong thing when we go with a half mil track width with metal particle tape just

because that gives us a hell of a lot more data on tape. Do our users really want just a hell of a

lot more data on tape, or do they want a reliable system? Do they really want to crossplay that

stuff when they ship it in from the Gull7 Or what do they want to do?

So, in the ID-1, we try to be as reasonable as we can and build in the tolerances that it

takes to make the damned things work. But we need advice from you guys. One of the biggest

problems I ever had with tape recorders was making the damned media work.

(Laughter)

MR. ROBINSON: On the system 600, we went through two or three tapes to get the

quality we needed -- finally solving all of our problems. The media is important; and

tolerances are important on tracking--very important.

And I don't know where we are going to stop, you know; maybe with barium ferrite, we

can do half-mil write tracks.

MS. CARLSON: You are still going to be on polyester; you know, that's the driving thing.

(Inaudible discussion)

MR. ROBINSON: So, I think you media people should advise the recorder people to make

the tracks wide enough so these guys won't have the problem.

2-233
PARTICIPANT:(Inaudible)

DR.REAG6R:Andfrom my user'sstandpoint,wew0uld Iike to haveasmuchdataas

youcouldput in asquareinch ofmediathat will bethere20yearsfrom now;andI don'tcareIf i

put it underwater;I don'tcareIf I bum the buildingaroundit orwhatever--it'sthere.

With the phonesystemwehaveright now,if thereIs lightning andyour powergoesout,

youpick upyour phoneand It works. So,the phonecompanyhasthIs attitudethat whatthey

useto workwith thelff_-_sfemshouldbeth_ saTme. ...............

" £

So, from a user's standpoint, I agree with what you said. i can't tell you what to do; i_

just telling you what I want.

IVIR. ROBINSON: What we should do Is be conservative in design.

PARTICIPANT: (Inaudible]

MR. HADAD: Your statement Is absolutely correct. 1 percent Is something like 8/10ths

of a dB, and that doesn't bother an ECC system at all.

DR. SPELIOTIS: But on the other hand, most of these tapes are for real high density

environments; they operate at an error rate of 10 -5, with no correction. And 10 -4 is about the

limit for error correction to get you to i0 q2. In other words, you have an order of magnitude

roughly and degradation narrows the safety margin.

PARTICIPANT: I think that is an incorrect statement.

DR. SPELIOTIS: Why?

PARTICIPANT: Why9

DR. SPELIOTIS: Well, of the typical Reed-Solomon error correctors used require

tolerate input error levels of about 10 -4 , or maybe seven times 10 -3, before they fall off the

edge.

L: :ZZZ_L 22Z : ::

MR. CORCORAN: _Ifyou allow us enough overhead, we will bust it through to any level

that you want. Okay? On a terabit memory system, they used double recording and then record

over it. And I believe on one of the audio systems, they do the same thing. They double record

and then they record over that.

And they can get 10 -15 or 10 "16. In fact, it becomes very difficult to measure it.

DR. SPELIOTIS: Right, but what do you start with and what IS the limit?

MR. CORCORAN: I just gave you two examples, and I know that we can get up to almost

any number you want; it is just going to take more overhead. Most of the time, we are not

allowed I00 percent overhead.

We have seen recorders where we Were only allowed 10% overhead, 5% for ECC, The

lady in the back said: Well, you have all these different problems; and it winds up being a tradeoff between the different alternatives, and you are squeezed in almost every direction. And you

have to make a good Judgment.

L =C _ L

PARTICIPANT: (Inaudible)

MR- CORCORAN: Yes.

DR. KRYDER: Other questions?

2-234
PARTICIPANT:I wouldJustlike to makea statement. I'm surprisedsomebodyup here

hasn'talreadydoneso;andthat is that thecareandfeedingofmagnetictapeis not a new

subject.

I knowthat Ampexhasbrochuresthat theymakeavailableto customersthat say: Here

is howyou treatmagnetictape. Andthereis nomysteryto that. You don'tmistreat it, folks;

that's the basicproblem.

I'm afraidthe old iron oxidetapehasbeenforgivingenoughthat youmay havebeen

misledinto thinking that you canmistreat them.

PARTICIPANt.I wouldsuggesthat yougoback to your friendlydealerandpick up

their recommendationson howto treat the stuff. (Inaudible)

WhenIBMfirst cameoutwith their 3480tape,they shippedthat stuff in refrigerated

cars

MR.HADAD:Well,wearepushing the edge. People's requirements are greater; that's

true, and there are materials out there to make more robust tapes. But I don't think anybody

wants to pay for them; they are between $1,000 and $10,000 a reel. Yeah, we can probably make

a tape that is stable to everything; but nobody is going to buy it.

DR. MALLINSON: I have a question for Dennis. (Inaudible)

DR. SPELIOTIS: The recording performance is equivalent?

DR. MALLINSON: Yes.

DR. SPELIOTIS: The recording performance is superior. Barium ferrite is far superior

to MP at very high densities (above 80 KFCI)

!

(Inaudible discussion)

DR. KRYDEI_ Does anyone have anything else?

MS. CARLSON: To expand on what Dennis is saying, Just think about barium ferrite

particulates. If you go into Target or K-Mart, you can see VHS all over the place. The industry is

scaled up for particulate media. So, the cost per package is going to be much lower Just because

there is an industry that is all scaled up to manufacture, at very reasonable cost, particulate

media. With ME, you have to put the capital investment in in order to get your manufacturing

up to even 1% of the worldwide capability that we have now in particulates. So, that is going to

be a huge investment for the manufacturers, and they don't want to go out of business. It has got

to make very good business sense in order for that to happen.

(Inaudible discussion)

DR. KRYDER: Any other questions? Comments?

(No response)

DR. KRYDEI_ Okay. I want to thank the panel and thank the audience for all your

participation.

(Applause)

(Whereupon, at 6:25 p.m., the conference was recessed, to be reconvened on Thursday,

July 25, 1991 at 9:00 a.m.)

2-235
iJ
N93-16331

19 mm DATA RECORDERS

SIMILARITIES AND DIFFERENCES

by

STEVE ATKINSON

AMPEX CORPORATION

PRECEDING PAGE BLANK NOT FILMED

2-237
2

!
19 mm DATA RECORDING FORMATS

Confusion over the use of non-video 19 mm data recorders is becoming more

pronounced as we enter the world of high performance computing. What is the difference

between ID-1, ID-2, MIL-STD-2179 and DD-2? What is the proper machine for my

application? How do I integrate it into my environment? These are all questions the user

community needs answered. This paper attempts to address these issues and clear up any

misconceptions there might be about 19 mm tape recorders.

HISTORY

The MIL-STD-2179 and ID- 1 tape formats are modifications of the D- 1 tape

format standard used in the television and motion picture industry. The development of D 1

based instrumentation standards was driven by the need of military and government users for

high speed digital recorders to capture data. The Military Standard 2179 (MIL-STD-2179) was

supported by a group of manufacturers and military representatives (primarily the United States

Navy) to provide such a recorder. The first prototypes of these recorders are becoming

available now for Beta testing in a number of military programs. Loral, Sony, Datatape,

Honeywell, and Schlumberger are all working to deliver these machines. An ANSI standard

known as ID-1 also exists which is being implemented by same manufacturers. It differs

slightly from the 2179 implementation but is not interchangeable due to the use of azimuth

recording, which is not used in the D1 TV format or the MIL-STD-2179 format.

Products to support the television D1 format became available in early 1987 and

were followed by D2 format products in late 1988. The two TV digital formats differ in that

D I supports component recording while D2 supports composite recording. In laymen's terms,

this means that D1 records video as individual data streams and D2 records it as a single

stream. The Ampex ID-2 product is based upon the unmodified D2 NTSC video format, but is

supplemented with user interfaces specific for instrumentation applications. As such, the

Ampex ID-2 products can serve as either a video or instrumentation recorder. D I recorders are

produced for the video industry by Sony and BTS and D2 recorders are manufactured by

Ampex with Sony and Hitachi. The D2 recorder is the dominant 19 mm machine in the video

industry constituting over 75% of the digital market today and is expected to increase in market

share to over 80% by the early 90's.

The need to support high speed data storage and retrieval for the supercomputer

industry was identified by Ampex as a major market opportunity as data creation and storage

grew exponentially in the 1980's. Hence, the Data D2 (DD-2) development was undertaken as

a joint development by Ampex and E-Systems. The basic difference between the DD-2

recorder and instrumentation recorders is that DD-2 is designed as a computer peripheral with

computer interfaces and file structures as opposed to an instrumentation recorder which records

input as a single uninterrupted stream of data. Each class of machine has its strengths and

weaknesses depending on the mission the user wants to accomplish.

COMMON FEATURES

DD-2, MIL-STD-2179, ID-2, and ID- 1 physically record data in very similar

manners. All implementations use a recording technique know as helical scan. Helical scan

recorders lay down data at an angle on tape and provide improved storage density over

longitudinal formats and also provide powerful error correction capabilities. Ampex was a

pioneer in the helical scan technology used in today's home VCR's.

Each of these scans of recorded data are called tracks. They are grouped

together to form track sets, the lowest addressable unit of data from a physical standpoint. The

2-239

tECEDING PhGE BLAr, I_. NOT FILM_ED
helical scan data tracks are accompanied by three longitudinal tracks. In the video version,

these tracks contain control, time code and audio information. The instrumentation and data

recorders use these tracks for control, timecode, and for file labels in the case of DD-2.

All four 19 mm formats are implemented in high performance machines with

several versions tailored for specific missions. Featureg_dmthonly supported include high rote

data storage and retrieval, robotic compatibility, and positioning to data at speeds of 30 to 60

times playback speed. For DD-2 at 60 times playback speed, this translates to over 800

megabytes per second (Ml3/s) or the equivalent of four 3480 cartridges every second.

With these similarities in mind, it is easier to discuss how the DD-2 computer

storage peripheral and 19 mm instrumentation recorders use the 19 mm platform to accomplish

different tasks with different derivations of the same basic technology.

INTERFACES : "

_eaPplications=for=instrumentation recorders such as ID-1, and computer

peripherals such as DD-2, drive the design of their interfaces. Instrumentation machines are

commonly used for data capture which means that data will come in a continuous stream with

the recorder turned on when the data starts and off when the data stops. This alleviates the

need for any buffering on the recorder since the data should arrive in a continuous mode at a

steady rate. The standard implementation is a 16-bit wide data front-end which operates in a

synchronous mode. By implication, this means that the recorder operates as the master with

the input or output source acting as the slave. This is because the recorder expects to record

and retrieve data at a steady, uninterrupted stream. Typically, it handles different data rates by

the ability to record/retrieve data at selectable, binary rates of up to approximately 30 MB/s in

some implementations. Therefore, it is up to the source to buffer the data for smoothness

within a small percentage of the recorder's data rate needs. While this is a good

implementation for the field and downlink data recording it was designed for, it poses severe

problems in a computer environment.

Most computer operating systems simultaneously execute multiple programs in

an interactive, time sharing environment. Input and output to a peripherai is not supported as a

steady, uninterrupted stream, but instead is dependent upon the dynamics of system loading,

computational rates, and application mix. These operating environments do not include the

dedicated data buffering and strict command scheduling required to match rates with a data

peripheral. The logic of these operating systems is designed to use compute cycles to serve

applications -- not peripherals.

Instrumentation recording on a computing platform requires a dedicated

computer, executing only from a predetermined set ofc0ntrolled appiications. Development of

instrumentation interfaces, controllers, and special device drivers are required to connect a

given peripheral. Memory must be dedicated to support the strict input/output rates of the

peripheral.

The DD-2 recorder was designed with these interface shortcomings in mind.

The DD-2 recorder from Ampex uses the ANSI standard Intelligent Peripheral Interface Level 3

(IPI-3) interface to send data to and retrieve data from the recorder. This standard computer

interface defines command, control, and status for both disk and tape peripherals. The subset

of the IPI-3 command set dealing with tape devices is used for the DD-2. A large buffer is

included as part of the interface electronics. This buffer performs the rate smoothing to provide

a sustained data rate of 15 MB/'s with a burst rate of 20 MB/s. Using the _!-3 command set

and the buffering capability allows the host to request data units as smai i _ a s_gie byte so that

the host computer does not have to retrieve an entire physical block. The IPI-3 implementation

also allows up to 8 recorders to be "daisy-chained" on a single control interface. While one

recorder is transferring data, the others can be given positioning commands to minimize the

2-240
time spent waiting for the subsequent file transfers. Other standard interfaces will be supported

in the future. In summary, the DD-2 looks like a standard tape peripheral to the host computer.

DATA FORMAT

As stated earlier, both DD-2 and 19 mm instrumentation recorders physically

record data on tape in very much the same way, helical scans grouped as track sets. Once

again, the differences lie in the fact that the DD-2 is a computer peripheral recorder. Both

machines can retrieve data by track sets if that is the search parameter they are given. The DD2 also makes use of the longitudinal tracks to implement ANSI 9-track file labeling. Files on

the DD-2 can be retrieved by using file labels rather than track set ID's. This allows software

already developed on the host computer to manipulate 9-track tape and 3480 cartridges to also

make use of DD-2 cassettes. Minimizing the impact of incorporation of DD-2 into existing

computer is one ofthe highest priorities of the DD-2 development.

The traditional concept of tape volumes is incorporated into the DD-2 design

while not in 19 mm instrumentation formats. Each DD-2 physical cassette looks like one or

more logical volumes to the host computer. These logical volumes can be edited and appended

to look like traditional 9-track volumes. Ano!her somewhat related innovation is that the

cassettes can be loaded and unloaded without rewinding to beginning of tape or end of tape.

This greatly decreases the amount of search time spent positioning to the beginning of a file.

Inter-record gaps are another format difference between 19 mm instrumentation

recorders and DD-2. Because most 19 mm instrumentation machines record data at binary

rates, the gaps between recorded data are of variable size. This leads to less efficient use of

tape as it is indeterminate how much tape is left unrecorded in between data records. The DD-2

uses a consistent gap to further improve upon the substantial data density advantage DD-2

holds over the ID- IAVIIL-STD-2179 class of recorder.

ERROR RATE

Image capture and retrieval is one of the most common uses of ID- 1 and MILSTD-2179 recorders. When manipulating images on a host computer, errors on tape can be

recovered from by reconstructing the lost part of an image from the remaining parts which

surround it. For that reason, the Bit Error Rate (BER) of 10 "1° specified for MIL-STD-2179

and ANSI ID- 1 recorders is sufficient for most of the applications in which it is used but may

require tape certification to achieve. This BER is not always adequate for computer

applications. DD-2 will deliver an error rate approximately three orders of magnitude better by

guaranteeing less than one error event in every 10"12bytes read.

All commercial 19 mm recorders have the capability to read what has been

written on tape immediately after it is written. However, the implementation of a data buffer in

the DD-2 interface makes verification of the data written on tape possible. When an

uncorrectable error is detected by the read-after-write verification function; the data will be

rewritten to tape a selectable number of times by the DD-2 controller. When retrieved, invalid

data is ignored with only the corrected data returned to the host. This capability is coupled with

three levels ofpowerful Reed-Solomon coding to achieve the improved error rate over 19 mm

instrumentation formats. For example, the extended burst correcting capability of DD-2

provides a 50-times improvement over ID- 1, minimizing errors due to tape defects.

In addition, the DD-2 will monitor the stress level of the error detection and

correction (EDAC) equipment and store the statistics in the recorder. When requested from the

host computer, it will be returned as status. In this manner, the host can monitor the "health"

of an individual cassette and record the data contained on it to a new cassette when appropriate.

2-241
MEDIA

The media used by data storage peripherals and instrumentation recorders is the

same as used in the video industry. The cassettes used by all 19 mm recorders contain tape

which is 19 millimeters wide (about 3/4 inch). The main difference is that DD-2 and ID-2 use a

metal oxide based tape with a total thickness of 13 micrometers, while the ID- 1 and MIL-STD2179 use the older iron oxide formulation with a total thickness of 16 micrometers. 19 mm

cassettes are very similar in appearance to home VHS cassettes except that VHS uses 1/2 inch

tape. D2 tape is manufactured by Ampex, Sony, Fuji, and Maxell with 3M expected soon to

enter the market. D1 tape is available from Ampex, Fuji, and Sony. The important point is

that both are supported by more than one source which should result in both a reliable future

supply and low user costs.

The storage density of D 1 and D2 based recorders is a function of the recorder

and tape used. A storage density comparison is contained in this section for simplicity's sake.

Both DD-2 and ID-1/MIL-STD-2179 have three sizes of cassettes: small, medium and large.

The small D2 cassette contains 25 gigabytes (GB) of user data with a medium containing 75

GB and a large holding 165 GB. This comp_/res to 14 GB, 44 GB, 92 GB for the small,

medium, and large D l cassette_ respectively.- T :_ .....

A concern has been raised on the shelf life of metal oxide tape due to the high

content of iron particles in the tape. Metal particle tape has been in existence over i5 years and

has been used in commercial products for over 10 years. All 8 mm Camcorders, as well as

other video and data storage products, are based on the metal oxide tape. Ampex has recently

completed accelerated life tests which simulate a 14-year archive. No degradation in BER or

magnetics was detected with the tape in the cassette. Deifiils were presenied by Ampex at the

Tape-Head Interface Conference (THIC)proceedings on 9January I991. Copies of the

presentation are available from" Ampex. Tests by other manufacturers also support these

results.

SUMMARY

DD-2 and 19 mm instrumentation recorders have missions for which each is

well designed. While the differences may appear subtle, understanding the difference between

the two is the key to picking the right recorder for your particular application.

5i

2-242
- . _ k

N93-]6332

DATA STORAGE AND RETRIEVAL

SYSTEM ABSTRACT

by

BARBARA MATHESON

STX CORPORATION

2-243

DATA STORAGE AND RETRIEVAL SYSTEM ABSTRACT

The STX mass storage system design is intended for environments requiring high speed

access to large volumes of data (terabyte and greater). Prior to commitment to a product

design plan, STX conducted an exhaustive study of the commercially available off-theshelf hardware and software. STX also conducted research into the area of emerging

technologies in networks and storage media so that the our design could easily

accommodate new interfaces and peripherals as they came on the market.

All the selected system elements were brought together in a demo suite sponsored jointly

by STX and ALLIANT where the system elements were evaluated based on actual

operation using a client-server mirror image configuration. Testing was conducted to

assess the various component overheads and results were compared against vendor data

claims.

The resultant system, while adequate to meet our capacity requirements, fell short of

transfer speed expectations. A product team lead by STX was assembled and chartered

with solving the bottleneck issues. Optimization efforts yielded a 60% improvement in

throughput performance.

The ALLIANT computer platform provided the I/O flexibility needed to accommodate a

multitude of peripheral interfaces including:

Up to twelve 25MB/s VME I/O channels

Up to five HiPPI I/O full duplex channels

IPI-2, SCSI, SMD and RAID disk array support

Standard networking software support for TCP/IP, NFS, FTP.

Open architecture based on standard RISC processors

V.4/POSIX-based operating system (Concentrix)

Standard 1 Terabyte System:

Alliant SRM-1 computer with approximately 100 GBytes of

user online storage (capable of expansion to over 1 TeraByte)

in the maximum strategy arrays and one point-to-point link for

a Cray supercomputer using the UItraNet link to provide up to

50 MBits/s transfer and a STK 4400 ACS with one LSM and

a 2-controller CAS with eight transports (four transports for

PRECEDING P_IGE BLANK NOT FILMED

2-245
archiving and four transports for backup to provide a backup

transport for each function).

This configuration distributes I/O over four VME data paths with each bus providing a

sustainable transfer rate of 40 MBytes to memory and 24 MBytes from memory. Three

VME chassis are used to provide four data paths by subdividing one chassis into two

paths, yielding a total of 29 device slots. The described configuration uses 14 slots,

leaving 15 space slots that can be used for a mix of additional disk arrays, network

interfaces or archival read/write stations.

Aside from performance requirements, the companies surveyed many candidate users

to determine other features and benefits that would be valuable to an end-user. The

most common concern was that a-syTstem put in place today still be viablein 5 years,

Our product team then turned its attention to growth path issues to ensure that newer,

higher speed network architectures could be accommodated and that new storage

technologies could be added as they became available.

All C0mpo_ents including the s0_wareare modular in designand can be reconfigured as

needs and system uses change. Users can begin with a small system and add modules

as needed in the field. Most add-ons can be accomplished seamlessly without revision,

recompilation or re-linking of software.

Since the software is device-dependent only at the lowest layer, new interfaces and

peripherals can be easily accommodated.

On.qoing development is focused on:

• Implementation of HiPPI capability

• Selection and interface of D-l, D-2 tape systems

• Interface to Metrum RSS-600

• Interface to SUMMUS//MAGNUS tape jukebox

5

2-246
2-247
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2-248
2-249
L

i
N93-16333

OPEN SYSTEMS STORAGE PLATFORMS

by

KIRBY COLLINS

CONVEX STORAGE SYSTEMS

PRECEDINO_ P_GE F_LAI',I]_ N'OT FIL,_,,_E_

2-251

Open Systems

Storage Platforms

Storage Applications

ConvexOS System Software

High Performance Peripherals

DS Series Data Server Systems

;_'!-_i z_=_'%.=_.

The builcfing blocks for an open storage system includes a system

platform, a selection of storage devices and interfaces, system

software, and storage applications

CONVEX storage systems are based on the DS Series Data

Server systems. These systems are a variant of the C3200

supercc "nputer with expanded I/O capabilities. These systems

support a variety of medium and high speed interfaces to networks

and peripherals. System software is provided in the form of

ConvexOS, a POSIX compliant derivative of 4.3BSD UNIX.

Storage applications include products such as UNITREE and

EMASS.

PRECE!!3'INGP,_GE BLANK NOT FtLMED

2-253
DS Series Systems

(cPu 1

cpu2 3

R 2OO

CPU 3 ?

R 2O0

2 Gbyte

Multiporte¢

Memory

J

I

IIii

PBUS aoM_X,,,_=

IIII

II

up to 14

VME, IPl, RPS-60

or HiPPl channel

controllers II

The pert,_rmance of the DS Series is driven by the main memory

system, a multiported arrangement with up to 2 Gigabytes of RAM

and a total bandwidth of 800 megabytes/second. A crossbar

connects this memory system to five 64bit wide ports, each

capable of transferring data at up to 200 megabytes/second. In a

C3200 supercorni3uter, four of these ports are dedicated to CPUs,

with the 1;fthattached to the I/O system, in the DS Series version

of the architecture-, two memory ports are allotted to I/O and only

three CPUs are supported.

The I/O system is'designed around a high speed I/O bus Called

the PBUS. Each memory port supports two PBUS's, for a tOtal of

four in the DS Series. The PBUS in turn supports intelligent

channels, each of which supports one or more VME, IPI, FIPS-60,

or other types of standard l/O busses.

k

2-254
Peripherals - Tape Systems

ITC

IPl-3

Channel I Ampex

Rg0

Recorder

D2 format tapes

25 gigabytes per tape

15 Mbyte/sec transfer rate

TLI II_m_ _rLI"_3 STK silo

FIPS-60 _ up to 6000 3480 cartridges

Channel

VIOP

VME

Channel

A range of tape systems is available as well - again based on

industry standard interfaces.

A channel controller wiii soonbe available which generates four

IPI-3 channels, which can be used to interface such devices as

the Ampex R90 DD2 recorder. This device uses a tape format

based on video broadcast technology to store from 25 to 150

gigabytes per tape, depending on cartridge size, with transfer

rates of up to 15 gigabytes/second.

The TLI generates two FIPS-60 (IBM Block Mux Channel)

interfaces, and can be used to connect to such devices as the

Storage Technologies ACS (popularly known as the silo) or high

duty cycl_ 3480 compatible tape transports.

Lastly, VME cards can be used to interface to lower speed devices

such as nine track tapes, or SCSI based devices such as DAT or

medium duty cycle rack mount 3480 compatible drives.

2-255
Peripherals- Disk Systems

IDC

IPl-2

Channel

Controller

Seagate 1 Gigabyte

yes, 6Mbyte/sec

each IDC supports up to 32 drives,

up to a total of 255 In system 4 IPI-2 channels _ --

VIOP

VME

Channel

1 Gigabyte SMD drives

RD$ removable

disk systems

CONVEX suppor{s three-basic kinds of disk systems.

High performance IPI-2 disk drives are supported via the IDC, an

88000 based integrated channel controller which generates four

IPI-2 interfaces, each capable of transferring data at up to.!0

megabytes/second. Each of those interfaces can support up to 8

disk drives, for a total of 32 per IDC. With multiple IDC's more

drives can be attached, _up to the System maximum o(2551 ]--hesystem is capable of transferring data into tl'iese drives at

aggregrate rates in excess of 50 megabytes per second.

Lower speed drives are supported via the VIOP VME channel,

which supports up to two VME busses with 10 megabytes/second

of bandwidth each. An SMD-E interface is available along with 1

gigab},_.e winchester drives, and an ESDI interface is also

supported for low cost 780 megabyte drives.

2-256

i

i '
Peripherals- Networks

-.,.:,;.;,,..

TcP/IP

FTP, TELNET

NFS

NCS

DECnet (Ethernet)

GOSIP (future)

HiPPl

(future)

VIOP

VME

Channel

Ultra Hub

1

.--._ _--v.E,F1

-----_FOO,,,= 'ro,I

I

Network interfaces are provided primarily through VME based

interface cardsl Controllers are-_.vailable for Ethernet,

HYPERchannel, and Ultra, with FDDi available in the near future.

A HiPPI channel is also planned in the near future, to interface to

the Ultra hub at high bandwidths, as well as other HiPPI based

devices and switches.

The operating system supports the most commonly used

protocols, such as TCP/IP, DECnet (Ethernet only), and GOSIP

(in the future).

2-257
ConvexOS ........ •.,.-.,,

I other

mpplications

1

!,,.I

pCOCeS8

management

J memory

management

storage applications

EMASS, UNITREE

filesystem

h tape 1 network

system services

services

services

device interlaces

\

The heart of any open systems strategy is the system software,

since it is compatibility at the system interface that allows a high

degree of interoperability and portability of storage applicatio0s.

ConvexOS is a derivative of 4.2BSD UNIX, updated with 4.3BSD

enhancements, and modified-to-be compliant with the POS1-X.I--

standa,'e. Semaphored for symmetric multiprocessing, it uses the

parallel architecture of the C3200/DS arcfiitectur6to_provide high

throughput undera heavy !/O 10ad. Exteffsions to the basicUNiX

filesyStem and tape services provide support for storage

applications suchas EMASS and UNITREE.

i

i

2-258
Disk Management ......,._

ufs

,ar

Virtual

Volume

Manager

storage

applications

/

raw disk

Disk Drivers

EMASS

UNITREE

• Partitions spanning up

to 128 physical drives

• RAID levels 0, 1, and 5

• Automatic regeneration

of failed drives

One clear trend in storage is towards large numbers of magnetic

disks. To ensure that the connection of!arge numbers of disk

drives does not reduce the overall reliability of a storage system,

ConvexOS provides a driver layer called the Virtual Volume

Manager (VVM).

VVM takes up to 128 physical partitions on different disks, and

combines them into one large partition to the file system and other

higher level applications. VVM interleaves successive blocks

across different drives to allow parallel access for sequential disk

I/O, and can generate mirror or parity blocks so that a failure of

any one disk does not cause loss of data. If a drive does fail, VVM

can reconstruct data blocks on a spare drive,so that the system

can tolerate a drive failure and return to redundant operation, all

without ;r,terrupting applications that are accessing the partition or

requiring operator intervention.

2-259
_=

=

File Fault Interface

ufs

r storage 1

I rpc J calls

Virtual

Volume

Manager

Disk Drivers

!¢!¢i .......

";:_:_';_...:!i;:'

• filesystem events can

trigger rpc calls to an

application

- file open, read/write

- metadata update

- block allocation

- space watermarks

• allows storage

applications to manipulate

files transparently to user

applications

One of the most difficult challenges in supporting a variety of

storage applications is how to tightly integrate these applications

with the host sYstem's own file system, since the host files_,stem

is usually highly tuned to the architecture, it may make sense to

use it for i0(_ai b-uffering of fiiesl especially _fthe host is als_sed

for compute intensive applications as well as-storage. Ma6ystorage applications have client code that is inserted in the kernel

of the host operating system. Providing support for client code for

very many storage applications is problematic, since there is little

uniformity in these interfaces.

To resolve this ConvexOS provides an interface which allows a

storage app_ion to trap many filesystem events, with

notification via RPC calls to a daemon process outside the kernel.

This allows a storage application to be notified of file creation and

access, and migrate data blocks into and out of the filesystem on

demand. This activity is completely transparent to applications

accessing files through the ConvexOS filesystem, and allows

hierarchical storage management to be implemented without

modification to applications.

2-260
Convex Storage Servers

,...+;,,....

• Assembled from off-the shelf components

• Industry standard interfaces

• Convex engineering for performance and

reliability

With the DS Series of storage systems, Convex has developed a

set of products which provide open systems solutions for storage

management applications. The systems are highly modular,

assembled from off the shelf components with industry standard

interfaces. The C Series system architecture provides a stable

base, with the performance and reliability of a general purpose

platform.

This combination of a proven system architecture with a variety of

choices in peripherals and application software allows wide

flexibility in configurations, and delivers the benefits of open

systems to the mass storage world.

*U.S.COVZ_J_ENTPIt[NT_COFRCE:z9s2 -?2e-osvssoos

2-261
|i!

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1. AGENCY USE ONLY (/.J_w b/_nk) I 2. REPORT DATE i 3. REPORT TYPE AND DATES COVERED

I September 1992 Conference Publication, July 23-25 r 1991

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

NSSDC Conference on Mass Storage Systems and Technologies for

Space and Earth Science Applications

Volume !I

Ben Kobler, P. C. Hariharan, and L. G. Blasso

7. PERFORMINGORGANIZATIONNAME(S)ANDADDRESSES)

NASA-Goddard Space Flight Center

Greenbelt, Maryland 20771

9. SPONSORINGIMONITORING AGENCYNAME(S)ANDADDRESS(ES)

National Aeronautics and Space Administration

Washington, D.C. 20546-0001

JON 933-656-80-02-26

S. PERFORMING ORGANIZATION

REPORT NUMBER

92B00093

Code 933

10. SPONSORING/MONITORING

AGENCY REPORT NUMBER

CP-3165,Vol. II

11. ,SUPPLEMENTARY NOTES

Kobler: Goddard Space Right Center, Greenbelt, MD;

Hariharan and Blasso: STX Corporation*, Lanham, MD.

*Hu_hes STX,Corporation as of October 1, 1991

12=.DISTRIBUTION/AVAII.ABIUTY STATEMEI_T

Unclassified - Unlimited

Subject Category 82

12b. DISTRIBUTION CODE

13. ABSTRACT (Maximum 200 words)

This report contains copies of nearly all of the technical papers and viewgraphs presented at the NSSDC

Conference on Mass Storage Systems and Technologies for Space and Earth Science Applications. This

conference served as a broad forum for the discussion of a number of important issues in the field of mass

storage systems. Topics include magnetic disk and tape technologies, optical disk and tape, software storage and file management systems, and experiences with the use of a large, distributed storage system. The

technical presentations describe, among other things, integrated mass storage systems that are expected to

be available commercially. Also included is a series of presentations from Federal Government organizations and research institutions covering their mass storage requirements for the 1990s.

14. ,?_IBJECT TERM_

Magnetic tape, magnetic disk, optical disk, mass storage, software storage

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OF REPORT

Unclassified

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OF THIS PAGE

Unclassified

19, SECURITY CLASSIRCATIO_

OF ABSTRACT

Unclassified

iS. NUMBER OF PAGES

269

le. PRICE CO0(

20, LIMITATION OF A_TRACT

UL

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