ITEM: U4347L

Can't restore a sysback 3.1 backup on a sysback 3.2 system

Env
  AIX 3.2.5
  sysback 3.2.1.11
  Tape: 8mm 5gb (7208-011)

Desc:
  Customer created a backup with sysback 3.0.0.34 (mkvgback)
  with a block size of 10240.  The customer always verifies
  his backups so we know the data was good at that time. 
  Now the customer, puts the newest version of
  sysback on his system 3.2.1.11 and can't restore with this
  version he is getting this error message:

  Unable to read the volume header on device /dev/rmt0.

  sbread -H /dev/rmt0
   Worked

  sbread /dev/rmt0 | restbyname -Tvqf-
    sbread: Error reading from device /dev/rmt0!
    sbread: Invalid argument
    restore: 0511-473 A unexpected end of file condition has occurred.
             There is no writer on the input pipe.

  I tries different block sizes 0, 512, 1024
  I can only read the header with 10240 using sbread -H /dev/rmt0

  I put back the older version of sysback 3.0.0.34
  and was able to read the tapes with no problem.  It appears
  to be a bug with sysback 3.2 with the sbread program.

I am able to reproduct this in the lab with a 4mm drive

Response:

The problem has been determined.  If the user is using 
sysback 3.1 and the backups are created with a block size
that is not a multiple of 64k like what the customer was doing making a
backup with 10k block size then if the customer upgrades to 3.2 of 
sysback they will not be able to read the data with the sbread command.
This is a rare type of problem and will not be fixed since fixing
it will cause more problems than what it solves.  Work around
is to keep a old copy of the sbread command from the older
version if you are to restore from a old backup (3.1 on a 3.2 with
this situation)

I see this situation is a rare one.



Support Line: Can't restore a sysback 3.1 backup on a sysback 3.2  system ITEM: U4347L

Dated: May 1995 Category: N/A

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