Re: [Xen-users] Xen, LVM and snapshots

[Ferenc Wagner <wferi@xxxxxxx>]

"Morten W. Petersen" <morten@xxxxxxxxxxxxxx> writes:

> We're considering using snapshots of LVM logical volumes as a backup
> feature, that is, having domU instances running on each of their own
> logical volume, and then in the dom0, create snapshots and take backups.
>
> Has anyone else tried this?  Is it safe?

If you snapshot an LV while it's being used by a virtual machine, then
your snapshot will be no better than what you'd get by powering off a
server.  That is, inconsistent data and dirty filesystems.  That means
your snapshot filesystem will have its journal replayed on mount, etc.
It may or may not be good enough for your purposes.

> I saw an old message from 2006 on this list, where it is said that
> "Common understanding is that LVM2 snapshots are unstable".

I don't understand this statement.
-- 
Feri.

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