From: lwatkins@jhunix.hcf.jhu.edu (Lee Watkins)
Newsgroups: comp.sys.next.misc,comp.sys.next.sysadmin,comp.unix.questions
Subject: HELP (please)! Errors trying to backup with dump to SCSI tape
Summary: this should be pertinent to LOTS of NeXT users...
Keywords: HELP dump backup tape SCSI
Date: 31 Jul 92 16:07:14 GMT
Followup-To: poster
Distribution: na
Organization: HAC - Johns Hopkins University, Baltimore


I looked in NeXTanswers and FAQs and the Net & Sys Admin manual and NeXT man 
pages for st, mt, etc. and found little of real help when trying to do a 
backup to a SCSI tape device.  This seems like a subject that would be of 
interest to almost every NeXT owner/user.

Well, I thought I had it figured out.  I borrowed a 1/4" SCSI tape drive from
a SPARCstation IPC, a 150Mb drive (it's stamped inside the tape bay).  
Plugged it into my NeXTstation (OS 2.1) and rebooted and it came up as a   
ARCHIVE VIPER 150 21531 whatever that means.  I can tar tapes to it just fine
as /dev/rst0, even used the demo of enTar sucessfully.  

When I go to do a level 0 dump (which I've never done, so I need to...) I 
found that it estimated over 7 tapes, when I only have a little over 350Mb
of files to backup.  This does not make sense if the drive and the tapes
are 150Mb (I am using Maxell MC-6150 cartridge tape).  

So I read the dump man page, and it explains how with various tape drives you 
have to tell dump to use the equivalent number of feet of tape that would be 
required if you were actually using the default 1600bpi 9-track tape. 1600bpi
amounts to 19,200 bytes per foot, so to get 150Mb on a tape I should specify 
to dump that the tape is 8214 feet in length. So I tell it to use "almost" the 
whole tape, as shown in the man page for dump example for the Exabyte tape 
drive. Am I making sense?  

Anyway, it does not work, I get the following error:
----
nextlee# mt -f /dev/rst0 status
Generic SCSI tape drive, residual=0
Sense Key       = 0x05
Sense Code      = 0x00
Sense Byte 0x13 = 0x00
Sense Byte 0x14 = 0x00
Sense Byte 0x15 = 0x00
Sense Byte 0x16 = 0x00

nextlee# dump 0usf 8000  /dev/rst0 /
  DUMP: Date of this level 0 dump: Fri Jul 31 11:17:47 1992
  DUMP: Date of last level 0 dump: the epoch
  DUMP: Dumping /dev/rsd0a (/) to /dev/rst0
  DUMP: mapping (Pass I) [regular files]
  DUMP: mapping (Pass II) [directories]
  DUMP: estimated 299194 tape blocks on 2.21 tape(s).
  DUMP: dumping (Pass III) [directories]
  DUMP: Tape write error 0 feet into tape 1
  DUMP: NEEDS ATTENTION: Do you want to restart?: ("yes" or "no") 
----
Notice that it now seems to want about the right number of tapes (I have
three tapes sitting here ready to go). I try to restart, put in a different
tape, I tried powering off/on the tape drive, rebooting my whole system,
etc.  I am now at an impasse. WHY DOES THIS HAVE TO BE SO OBSCURE? 

Other info:  I did a fsck before doing dump, as it suggested in the Admin
manual--no problems there.  I booted in single user mode to do the the dump 
(although the above error was done in a shell window on root).

Any help would be greatly appreciated.  In fact, once I get this figured out
I would be perfectly glad to write it up in excruciating detail for NeXT-
Answers.

Lee Watkins, Jr.
JHU Homewood Academic Computing

P.S.-I am not a UNIX guru, or a sysadmin, just a mid-level manager in a   
computing organization with a NeXT on my desk.