[linux-lvm] Is it possible to invalidate snapshots other than by overfilling?
jbrassow at redhat.com
Wed Jul 2 15:42:58 UTC 2008
It sounds like the module needed by device-mapper to support snapshots
is not loaded when it is needed. (Perhaps the module - dm-snapshot -
is not in your initrd image?)
After step 3, but before step 4, try doing a 'dmsetup table' to see if
things are properly mapped. A 'dmsetup status' wouldn't hurt either...
Certainly, there should never be a kernel oops... It's tough for me
to say whether this bug is already fixed - given the age of your kernel.
On Jul 1, 2008, at 4:10 PM, Rob West wrote:
> Does anyone know of ways that snapshots can become invalid other
> than by writing more to the origin than the COW device can hold?
> The reason I ask is that we're having cases where a snapshot is
> becoming invalid, but we are very skeptical that it is due to
> overfilling. The size of the origin is 83G, and the size of the
> snapshot is 8G.
> Here's what little we can tell from the logs:
> 1. Backup script creates a snapshot and starts copying data from it.
> 2. Before backup is finished (and thus, snapshot removed), the user
> 3. On reboot, we get the following message which seems to be normal
> for this kernel:
> kernel: device-mapper: table: 253:2: snapshot-origin: unknown
> target type
> 4. About 23 hours later, the backup script tries to create the
> snapshot again but fails b/c it's still there.
> 5. The backup script tries to clean up by removing the snapshot, but
> lvremove causes a kernel oops because the snapshot is invalid. (We
> have identified a potential patch for this, but are trying to figure
> out why the snapshot was invalid in the first place.)
> The kernel we're using is based off of Fedora 6 (2.6.18-1.2849).
> Not sure whether it matters, but device-mapper is version 1.02.07
> release 4.0.RHEL4 and lvm2 is version 2.02.06 release 6.0.RHEL4.
> Thanks for any help,
> linux-lvm mailing list
> linux-lvm at redhat.com
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
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