Niall O Broin hath declared on Friday the 02 day of February 2007 :-:
> I've been looking into doing offsite backups of running xen VMs. The
> method being considered is making a snapshot of the VMs disk,
> mounting this, and then rsyncing it to the backup server. This has of
> course a number of issues with regards to consistency e.g. status of
> database files etc. Some of these are easy to solve (in the case of
> databases, doing some kind of dump before the snapshot is made, for
> instance) but some are not so easy e.g. files which are being edited
> just as the snapshot is taken.
Databases can be locked/flushed/dumped.
Most editors work in a temporary/swap file, so there should be a consistant
copy of the file since the last save, new changes will be lost, although
some might be recovered from the swap file.
> One issue I have noticed is that of filesystem inconsistency, the
> snapshot of course being at a lower level than the filesystem. TO
> deal with this, I have been running fsck on the snapshot, which has
> worked so far, but I guess it's only a matter of time before I get a
> filesystem state which fsck can't automatically handle.
xfs_freeze will suspend an (xfs) filesystem and flush buffers leaving
a consistant state on disk. Allowing you to create a snapshot with lvm.
I haven't used it in anger, but seems to work well in testing.
Mr. Rogers could explain shoe-tying and make it seem like the coolest
thing in the world. He was our Uncle and older brother. He told us we
were special, and we knew he'd be there for us.
A cult leader, right down to the sneakers.
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