[linux-lvm] Strangenesses with snapshots, 0.9.1-beta6.
Andreas Dilger
adilger at turbolinux.com
Wed Apr 18 18:15:09 UTC 2001
AJ writes:
> Are you sure those files were in a consistant state when you took the
> snapshot? You really need to get your file system into a consistant state,
> otherwise the metadata could be partially written out when the snapshot is
> made. There are hooks put into the 2.4x series kernels for ReiserFS to
> allow it to prepare for snapshots...but i don't think ext2 uses any
> mechanisms like this. I don't know a whole lot about it, but that's what it
> looks like to me.
Well, before the LVM snapshot is created, it does a full sync of the device,
so the amount of metadata that could be out-of-date would be very small (if
any).
Granted, there is a possibility that the original data is corrupt, but
Vegard reports everything OK on the original filesystem. I assume that
e2fsck -f on the unmounted /dev/vg/nhome works OK?
> > cp: cannot stat `/mnt/backup/vegard/Mail/unix/openldap-general/314': Input/output error
> > cp: cannot stat `/mnt/backup/vegard/Mail/unix/openldap-general/315': Input/output error
> > cp: cannot stat `/mnt/backup/vegard/Mail/unix/openldap-general/316': Input/output error
> > cp: cannot stat `/mnt/backup/vegard/Mail/unix/openldap-general/317': Input/output error
> >
> > [ *** This is another strangeness *** ]
> > middagspynten:/mnt/backup/vegard/Mail/unix/openldap-general# ls -l
> > .....
> > -rw------- 1 vegard vegard 3454 Dec 11 1999 309
> > -rw------- 1 vegard vegard 4530 Sep 9 1999 31
> > -rw------- 1 vegard vegard 4147 Dec 11 1999 310
> > -rw------- 1 vegard vegard 3294 Dec 11 1999 311
> > -rw------- 1 vegard vegard 3452 Dec 11 1999 312
> > -rw------- 1 vegard vegard 5775 Dec 13 1999 313
> > -rw------- 1 vegard vegard 3292 Dec 22 1999 318
> > -rw------- 1 vegard vegard 4318 Dec 22 1999 319
> > -rw------- 1 vegard vegard 4384 Sep 11 1999 32
The same files with IO errors are those missing from the directory listing.
Based on the file timestamps, I would assume that these files have not
been changed in a long time, so it is not a metadata consistency issue.
Cheers, Andreas
--
Andreas Dilger \ "If a man ate a pound of pasta and a pound of antipasto,
\ would they cancel out, leaving him still hungry?"
http://www-mddsp.enel.ucalgary.ca/People/adilger/ -- Dogbert
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