[Help-tar] Incomplete tape $>tar --verify -cvf /dev/st0 .

[jcalfee]

tar --verify -cvf /dev/st0 .

We are using this command to write directly to a tape.  This writes a single 
uncompressed archive to tape.  This works fine 6 out of 7 times.  About once a 
week though the end of the tape is incomplete.  

We are alerted by errors during the Verify pass:
...
Verify ./pmp/Order_MDDB_DRUG.pmp
tar: /dev/st0: Cannot read: Input/output error
tar: /dev/st0: Cannot read: Input/output error
tar: /dev/st0: Cannot read: Input/output error
tar: /dev/st0: Cannot read: Input/output error
tar: /dev/st0: Cannot read: Input/output error
tar: /dev/st0: Cannot read: Input/output error
tar: /dev/st0: Cannot read: Input/output error
tar: /dev/st0: Cannot read: Input/output error
tar: /dev/st0: Cannot read: Input/output error
tar: /dev/st0: Cannot read: Input/output error
tar: /dev/st0: Cannot read: Input/output error
tar: /dev/st0: Cannot read: Input/output error
tar: Too many errors, quitting
...
This time, there were 5 small files or 3,156 unrecoverable bytes.

When I try to restore this tape, the behavior is identical with the above 
errors appearing right at the end of the tape.

>mt setblk 0

Putting the drive into variable length block mode seems to fix the problem.  
I'm not sure why though.  The tape is in its default 512 block size while tar's 
default is 10240 bytes as a default.  I'm reading that since these values 
divide cleanly they should be compatible.

This is tar version 1.13.25.  I do not see any fixes or changes that would help 
in newer releases.  Have I missed one? http://www.gnu.org/software/tar/#releases

This is the tape drive:
# mt status
SCSI 2 tape drive:
File number=0, block number=0, partition=0.
Tape block size 512 bytes. Density code 0x26 (DDS-4 or QIC-4GB).
Soft error count since last status=0
General status bits on (41010000):
 BOT ONLINE IM_REP_EN




--
This message was sent on behalf of address@hidden at openSubscriber.com
http://www.opensubscriber.com/messages/address@hidden/topic.html