ITEM: V8755L

Sysback BACKUP MEDIUM I/O ERROR: read/seek: Bad file number

Env:
  AIX 3.2.5
  Tape DLT (Cambex)  using the OST device driver
  sysback ver 3.2.1.24

Desc:
  Customer is backing up a complete volume group of
  about 16gb of data
  to this tape drive that can hold up to 20gb of data.
  It fails consitantly
  on a 2gb file with this error message:

BACKUP MEDIUM I/O ERROR: read/seek: Bad file number
 Use a new disk and rerun the backup
 No writer on input pipe.

Action:
  The customer has 3 filesystems that are 2gb in size,
  each has a 2gb file in them
  The command mkvgback -vf /dev/rmt0 \
  will backup both 2gb files, but fail on the third one every 
  time. Checked the error log, no errors.  Also the customer 
  ran a fsck on each filesystem.

   Had the customer backup each filesystem one at a
   time with no problems using the
find ./\ -print | backup -ivqf /dev/rmt3.

   I had the customer do this:

1.  Start the mkvgback -vf /dev/rmt\# \
2.  Once it starts backing up files
3.  cd /tmp
4.  cp 1223filelist new_name
5.  CTRL C the mkvgback command
6.  cat new_name | backup -ivqf /dev/rmt0
    This failed at the same point with the same error as above.

So the problem is not with sysback/6000 sbwrite
command, but with the backbyname command.
Sysback/6000 ver 3 using this method on backups
cat filelist | backup -ivqf- | sbwrite -S /dev/rmt\#

There is a APAR that addresses this problem:

APAR: IX46291

PROBLEM:
The backup program fails with:
 "BACKUP MEDIUM I/O ERROR: read/seek"
 "Use a new tape and rerun the backup"
 on a 3490 tape drive.  This is a tape drive
 that holds multiple tapes, but present it is acting as
 a single volume.

PROBLEM CONCLUSION:
 The internal counter which keeps track of the
 amount of data written to tape became negative
 due to the large amount of data being backed up.
 Changed the counter to be unsigned and compressed               
 the counter. 

Ordering the fix for the customer U435126    

           



Support Line: Sysback  BACKUP MEDIUM I/O ERROR: read/seek: Bad file number ITEM: V8755L

Dated: June 1995 Category: N/A

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