From: John F Riordan (jriorda2@CSC.COM)
Date: Thu Dec 05 2002 - 11:55:31 EST
Hi all,
Was wondering if anyone could explain the following problem I had with tar.
I know what happened but am unsure why tar would do what it did.
Scenario:
We have an application using a Universe database, and yesterday several
files were corrupted. After doing some research and testing the files were
corrupted from a backup that was being run at 1:00am.
I was using a mounted file system ( /expbackup ) from one RS/6000 (rs6k01)
to an other RS/6000 ( /impback ) (rs6k02) for an occasional backup.
I was a backing up a directory ( /u1/data )of about 800MB on (rs6k02) to
the mounted directory ( /impback ) which is coming from ( rs6k01). Hope I
am not making this more difficult than it is.
The tar command I am using is the following: " tar cvf - ./u1/data |( cd
/impback ; tar xvf - )"
Everything is fine unless the NFS mount is broken from (rs6k01).. If the (
/expbackup ) becomes unmounted before unmounting it from (rs6k02) the
filesystem still shows as being mounted on (rs6k02) however if you try to
change directories to ( /impback ) you get "invalid directory". That I
understand, as the mount point is lost. Ok, my problem is that when my tar
script is kicked off via cron it still runs. As you look at the output you
would see that the files are being added then extracted. However if you
look at the add directory and then the extract directory they are the same.
It's adding and extracting to the same file system. And every so often I
see the message "tar 0511-173 File ./u1/data/blah is not of expected file
size". It's not every file, but the files that return this message end up
being corrupted.
I have since changed the way that backup is run but I was wondering if
anyone could tell me what is going on when that message is being displayed.
Sorry, so long winded,
and as always Thanks In Advance.
John
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