[linux-lvm] mirror and snapshot incompatible
Jonathan Brassow
jbrassow at redhat.com
Tue Oct 28 20:56:46 UTC 2008
It is possible to do all the things you are asking through device-
mapper... but there is no easy way to do it. (and LVM does not yet
have the capabilities to manage this yet either.)
brassow
On Oct 27, 2008, at 9:28 PM, Yoav wrote:
> According to lvcreate, a snapshot of a mirrored volume cannot be
> created ("Snapshots and mirrors may not yet be mixed"). However,
> devmapper does not seem to have the same limitation when used
> directly (not through lvm).
>
> Is there a current reason for lvcreate to enforce this rather harsh
> limitation?
>
> What are the risks I'm taking by manually creating a dm-snapshot
> from a dm-mirror device? (of course I'm also replacing the dm-
> mirror device with a snapshot-origin of the actual dm-mirror device).
>
> If there is an actual reason for preventing this, what is the
> suggested way to consistently backup a mirror volume? Is there a
> way to temporarily take one of the mirror "legs" (mimage devices)
> offline in order to back it up, and resync it later?
>
> Yoav
>
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