Hi all.
Having run several backups, and gotten the hang of tape drives and using
tar to copy to the tape drive, I'm now curious as to some kind of
verification that it's actually working and not corrupting any data.
Because I don't have enough Hard disc space to actually extract the data
off the tape and then do a comparison, my preferred method is to
calculate the md5sums of the files both on and off the tape and compare.
However, if I do a tar xfO /dev/stO | md5sum then all I get is the
md5sum of the entire tar archive on the tape.
Therefore, does anyone know how I can go about calculating the md5sums
of the individual files from the tar archive?
Doing a tar tf /dev/st0 > list gets me the list of files on the tape and
then I should be able to do a (perl code):
@list = <LIST>;
foreach (@list){
print `tar xfO /dev/st0 $_ | md5sum`;
}
but I've just tried doing that for a single file that's at the start of
the tape and it seems to be reading the whole damn tape, after having
successfully extracted the single file. I was rather hoping for this to
take less than a fortnight to complete.
The verify option (-W) may be of use, it seems to do a file system
compare. Do people use this: is it a good indication of the validity of
the backup? It's spotted that the size and Mod time differed on a file I
deliberately updated. I guess I would really like both -W and the md5sum
checks.
Does anyone have any suggestions/comments?
Thanks,
Matthew
--Matthew Sackman Nottingham England
BOFH Excuse Board: Zombie processes haunting the computer -------------------------------------------------------------------- http://www.lug.org.uk http://www.linuxportal.co.uk http://www.linuxjob.co.uk http://www.linuxshop.co.uk --------------------------------------------------------------------
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