On Mon, Mar 10, 2008 at 10:43:18AM -0000, Karl Wagner wrote: > That is almost exactly what I was after. > > Just one thing though... If I was to just take a backup of the COW > device, assuming the underlying origin had not changed, would I just be > able to restore this? (i.e. gzip < /path/to/cowdevice > > /path/to/backupfile.gz and restore with zcat /path/to/backup/file.gz > > /path/to/cowdevice, or similar.) Would this work with a newly created > snapshot? (ie backup as above then lvcreate -s -n newsnapshot > /path/to/origin; zcat /path/to/backup/file.gz > /path/to/new/cow/device) > > I will just emphasize that the UNDERLYING ORIGIN WILL NEVER CHANGE, it > is never mounted, never used for anything except as a snapshot origin. won't work "just so." just because you are messing with the storage does not mean the in-kernel exception tables would be updated magically. I mean, the equivalent is to dd back a file system image backup below a mounted file system... it may be possible to lvcreate -s -n newsnapshot /path/to/origin dmsetup table $that-new-snapshot remember it. dmsetup remove snapshot. zcat image.gz > snapshot-cow sync!!! maybe rather zcat | dd oflag=sync dmsetup create snapshot with identical table again. that in theory should make it read the (just restored from backup) exeption table from storage again. but I never tried. and I think it is scary :-) -- : Lars Ellenberg http://www.linbit.com : : DRBD/HA support and consulting sales at linbit.com : : LINBIT Information Technologies GmbH Tel +43-1-8178292-0 : : Vivenotgasse 48, A-1120 Vienna/Europe Fax +43-1-8178292-82 : _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
