From: highnam@slcs.slb.com (Peter Highnam)
Subject: SUMMARY: O( terabyte ) tape system survey
Organization: Schlumberger Laboratory for Computer Science
Date: Wed, 22 Jul 92 17:44:07 GMT


I received three types of response:

    Pointers to printed surveys
    Informal survey
    Information on Ampex D2 -based systems (Convex,E-Systems)

Thanks for your help!
Peter

 Schlumberger Laboratory for Computer Science, PO Box 200015,  Austin,
 TX 78720-0015 ;;  512-331-3736  ;;  highnam@slcs.slb.com (Internet)


========================== POINTERS TO PRINTED SURVEYS =========

[A]
Damon Hart-Davis (dhd@exnet.co.uk) wrote a Mass Storage Survey for the 
May/June 1992 issue of Parallelogram.  The article includes a brief
discussion of software, a tape system survey, a non-removable media
survey, and vendor contact information (24 vendors).  Well worth getting
a copy of the article!  He also sent a proper subset of the tape table:

Mfr Product     |BW(MB/s)|H/W   |Capacity   |Medium

Ampex
    DST 600     |15--20 |SCSI-2 |25--165GB  |D-2 (25--75GB per tape).
    DST 800     |15--80 |SCSI-2 |25--165GB  |D-2.  Multiple tape mechanisms.

E-Systems
    EMASS 1200  |15--80 |       |3.5--25TB  |D-2 archive system.

Metrum
    RSS-600     |4      |       |6.2TB      |Uses VHS tape.  Archive system.
                                            |(10.4GB per tape.)
Sony
    DIR-1000L   |8      |       |96GB       |ID-1.
    DIR-1000M   |16     |       |96GB       |ID-1.
    DIR-1000    |32     |       |96GB       |ID-1.
    DMS-700M    |96     |       |30TB       |ID-1 M cassette archive system.


[B]
From: ranade@nssdca.gsfc.nasa.gov (Dr Sanjay Ranade)
Subject: State-of-the-Art Report on Mass Storage '92
Organization: Infotech SA Inc.

A detailed technical report on the Mass Storage market, technologies
and systems to help in making informed purchasing decisions. Not a
product catalog. Available from Infotech SA Inc. (301)-989-1785
(Voice) ; (301)-989-2290 (Fax) ; Price $195 plus shipping


===================== INFORMAL (BUT STILL EXTENSIVE!) SURVEY ==============

From: arlanf@ncsa.uiuc.edu (Arlan Finestead)
To: highnam@SLCS.SLB.COM

Peter,

  Hello!  Hopefully I can be of some help to you.  There are several products
available today that are D1 and D2 type products.  Ampex corporation sells 
the DST 600, which is a DD-2 19mm helical-scan tape format tape unit.  The
DST 600 accepts D2 cartridges that are small (25 GB), medium (75 GB), and
large (165 GB) in size.  The DST 600 has a sustained data transfer rate of
15MB/sec, and 20MB/sec in burst mode.  The DST 600 supports the IPI-3 and
SCSI-2 interfaces.  The DST 600 is available as a product today.

  Ampex also sells the DST 800, which is an automated cartridge library.  Based
on the DST 600, the DST 800 has a capacity of 6.4 terabytes (256 25 GB DST 600
series cartridges).  The DST 800 will only accept and store the small (25 GB)
cartridges.  The DST 800 can utilize 1 to 4 DST 600 tape units.  From what
Ampex is telling NCSA, the DST 800 will be in production Fall of 92.

  METRUM Information Storage has a Optical Tape Storage System, called the
HD 1000.  This technology uses a laser to record information onto optical tape.
This is a read-only system.  Each optical tape reel is capable of holding
1 TeraByte of data per 910m x 35 mm (very similar to 9-track "style").  Data
transfer rates range from 0 - 3MB/sec.  METRUM Information Storage claims
data life of 20 years minimum.

  METRUM Information Storage also has a 1/2 inch helical scan RSP-2150 tape unit
that uses T-120 cartridge tapes (i.e. the same ones that you use in a VCR).
 Each tape can hold 14.5 GB of data.  Data transfer rates for the RSP-2150
are 1.966MB/sec sustained and 4MB/sec burst.  Interfaces for the RSP-2150 are
SCSI and Pertec/Cipher.

  METRUM Information Storage has an automated cartridge library for the
RSP-2150;  it is the METRUM RSS-600.  The METRUM RSS-600 has a capacity of 600
T-120 cartridges, making the total capacity of the system greater than 1
TeraByte.  Each robot can utilize from 1 to 5 VLDS drives.   Interfaces the
robot supports are RS232C, SCSI, Ethernet, and HYPERchannel.

  E-Systems has a 19 mm helical scan tape drive, called the ER90.  The ER90
is very similar to the Ampex DST 600.  The ER90 has the same data transfer
rates and data capacity.  Last time I checked, the ER90 can use either the IPI
or the IPI-3 peripheral interface.  E-Systems has a automated carrtridge library
for the ER90.  It is called the EMASS 1200, or EMASS for short.  EMASS stands
for "E-Systems Modular Automated Storage System".  The EMASS has a capacity from
3.5 to 25 TeraBytes.  E-Systems achieves the 25 TeraByte level by chaining 
multiple EMASS systems.  A pass-through port allows sharing of ER90 tapes
between individual units.  The EMASS can support from 1 to 4 ER90 tape drives.
In a fully configured system there would be 16 ER90 tape drives.
  
[... stuff elided ...]

  Thanks!

Arlan L Finestead  (arlanf@ncsa.uiuc.edu)
Research Programmer
Mass Storage Development
National Center for Supercomputing Applications
University of Illinois - Champaign/Urbana
Work: 217.244.5553    Fax: 217.244.1987


======================== AMPEX D2-based SYSTEMS ===================

[A] 
From: "Phil Reinkemeyer" <phil_reinkemeyer@rwc_mac.ampex.com>

Peter,

I saw your request on Internet for information regarding high capacity computer
storage peripherals.

Ampex has developed a mass storage system based on a video D-2 transport
developed and sold by Ampex since early 1988 as the VPR-300.  The new mass
storage products are called the DST 600 Data Storage Drive and the DST 800
Automated Cartridge Library.  

The DST 600 uses 19 mm cartridges of three different sizes to provide 25, 75,
or 165 gigabytes of storage per cartridge.  It uses an ANSI standard IPI-3
interface and has a sustained throughput of 15 megabytes/second.

The DST 800 uses 2, 3, or 4 DST 600 drives in a jukebox style robotics system. 
Each drive still has an independent data interface that operates at 15 MB/s.  
The robot accesses up to 256 of the small (25 GB) cartridges for a total
storage of 6.4 terabytes.

The DST 600 is available now with connectivity to Convex C2 and C3 computers. 
The DST 800 will be available in limited quantities in 4Q92.  

[ .. stuff elided .. ]

If you have any additional questions, please call me at 415-367-2885 or e-mail
me back.  I'd appreciate you posting your summary of this on the net.

Thanks,
Phil Reinkemeyer
DST Product Manager


[B]
From: Doug Patrick on zeppelin.convex.com <dpatrick@zeppelin.convex.com>

E-Systems has (or will have) a product called EMASS.  It's a robotic
tape library system based on D2 tape.  E-Systems worked with Ampex on the
controller design for the drive, and now Ampex is selling the drives.
I believe Ampex is also working on some kind of robotic tape library
system.  The biggest EMASS system holds ~7.5 Pb of data. (1 Pb = 1024 Tb
= 1024*1024 Gb)

The basic R-90 drive (or ER-90 or AR-90, depending on who you buy it from)
handles three D2 cassette sizes: small (25 Gb), medium (75 Gb), and large
(165 Gb).

I did the R-90 device driver for the Convex machines.  Using a Convex,
we can sustain > 14 Mb/s to/from this drive with big reads/writes and
big files.  Our IPI board and R-90 driver software are available now,
but I don't know if Ampex and/or E-Systems are shipping production
drives yet.  (They're certainly shipping drives, but they may still be
beta; check with them.)

Doug Patrick
dpatrick@convex.com


[C]  I asked Doug a follow-up question about longevity and reliability..

> From: highnam@slcs.slb.com
>
>         I've heard mixed reports about the longevity
> of D2 (and D1) formats (I don't know if this means physically
> or simply the state of the image on the tape).  For me
> this boils down to how often I can read/write such a tape
> before I need to be concerned about my bits.
>
> Thanks, Peter

From: Doug Patrick on zeppelin.convex.com <dpatrick@zeppelin.convex.com>
Subject: Re:  D2 reliability/longevity

I think there are (at least) two issues here:

    1.  How many times can you re-write a tape?
    2.  Once written, how long does the data on a tape last?

Concerning issue 1, the R-90 drive that I used during device driver
checkout did not have a flying erase head.  It was designed for use in
the broadcast industry where they erased tapes with a bulk eraser.  I
believe Ampex has/had some plans to add a flying erase head, but I know
nothing of the status.

Without a flying erase head, the bit error rate (actually symbol error
rate for this drive) of the raw bits on tape gets lower with each
re-write of the tape.  After some number of re-writes, it's desirable
to bulk erase the tape.  In practice, we have tests the re-write the
same sections of a tape hundreds or thousands of times, and I didn't
have any problems with uncorrectable media errors.  Although the error
rate (I assume) got progressively worse with each re-write, between the
three levels of ECC on the tape and with re-read & re-write capability
of the drive firmware, it always manage to return good data.

But I believe the drives are only spec'd for a few re-writes before
you're suppose to bulk erase the tape, so I'd be careful with important
data.  This would be a good question for E-Systems or Ampex.

For issue 2, I don't know how long data on an individual tape is
suppose to last, but I've heard that EMASS will cycle through the tapes
at some interval, reading all the data, and if there are significant
level 1 or level 2 ECC errors, the data is copied to a new tape.  The
idea is that data should last forever, even if the tape doesn't.  I
have no idea how well this works, though.

> Thanks for your message, I presume that it's ok to include
> my (eventual) summary ?

Sure.  But most of what I've said about E-Systems or Ampex is hearsay.
I hope they can provide more information.

Good luck,

Doug Patrick
dpatrick@convex.com




-- 
 Schlumberger Laboratory for Computer Science, PO Box 200015,  Austin,
 TX 78720-0015 ;;  512-331-3736  ;;  highnam@slcs.slb.com (Internet)