tar -xvf returns 'directory checksum error'

[Michael Cline_1]

I am running HP-UX 10.20 (i know, i know) and am trying to use the housecleaning tapes from our data backup to restore the data backup directory to our system (catastrophic failure on our raid wiped our our directory containing the data backup software (DOH!). Anyway, I loaded the tapes the system made and when I do the following:

#mt -t /dev/rmt/7m rew
#mt -t /dev/rmt/7mn fsf 1
#tar -xvf /dev/rmt/7m

it starts to extract some files and even creates the correct directory (alexbkup) and then I get 'directory checksum error'.

Any ideas?

Thanks so much (in advance!)

[RAC_1]

What are these tapes?? Ignite??
You need tar command as follows.

tar -xvf /dev/rmt/7mn

(note the no rewind device)

[Steven E. Protter]

If its an ignite tape, you get theat error when you tar xvf without first winding the tape past the lif record.

Seems you have correctly done that, though you may ant to consult your procedure.

Seeing what you say, I'd say the tape is pretty useless.

SEP

[Michael Cline_1]

These are not ignite tapes. To be honest, I'm not sure how the tapes are archived since they are done automatically by the software. In the past, I believe we have recovered from this exact same scenario using tar...

[Michael Cline_1]

instead of 'tar -xvf /dev/rmt/7m' I used 7mn and I still got the same error. It starts tar'ing off the first few files, two of which are 1 block each and when it gets to the third, which is 67 blocks is when it fails....

[Rodney Hills]

Could it be a "cpio" tape.

Try-
cpio -itv >/rmt/7m

HTH

-- Rod Hills

[Rodney Hills]

CANCEL MY LAST POST!!

Should be cpio -itv
Rod Hills

[Robert Salter]

Have you tried to just read the contents of the tape with a tar tvf /dev/rmt/7mn ? If that fails, like stated above, bye bye tape.

Is that the only tape you use for the backups? No rotation?

[Kent Ostby]

Try pax, it is sometimes a bit smarter:

pax -rvf /dev/rmt/7m

[Tim Sanko]

You are one of the candidates for backupEdge from Microlite. I would suggest you download and install a demo copy and see if it can recover the archive... It is priced reasonably.


Tim Sanko

[Vincente Fernandes]

Try list the contents of tape first using
tar -tvf /dev/rmt/?m
to verify the contents of the tape
Probably a good idea to clean the drive with a cleaning tape

[Michael Cline_1]

actually, I contacted Computer Associates (software vendor) and the command I needed was:

#dd if=/dev/rmt/7mn bs=1024k | tar xvf -

This was able to read the tape and restore the data.

Thanks for all the help though!!

[Devender Khatana]

Hi,

Allthough the session you are trying to extract seems not do much anyway. But you forwarded the tape after rewind, this means there are multiple sessions on the tape. It could be either being a ignite backup or somebody has backed up multiple sessions on the tape.

Find out no. of sessions and then try all.

Finding out:-
Power recycle tape drive or eject/insert tape or use #mt -t /dev/rmt/7m rew
Then
#mt -t /dev/rmt/7mn fsf 1
#mt -t /dev/rmt/7mn status

( In the output status will tell you the no. of session from beginning of tape and then do the last two commands again, Untill your Status no is exceeding, you are going to next session, in the end just rew and then try to extract all sessions one by one)

HTH,
Devender

[Bill Hassell]

HP-UX tar cannot handle different blocksizes, thus the technique suggested by CA. However, pax should be able to both tar and cpio tapes with any blocksize.

[Suraj Singh_1]

Hi Michael,

I would have tried to find out the method by which the backup is being taken by the s/w (tar/cpio/pax etc...).

Once you are aware of the backup command, you can easily find out what command (and option) to use to recover !!!

Regards