[DRBD-user] Kernel Oops on peer when removing LVM snapshot

Robert Altnoeder robert.altnoeder at linbit.com
Mon Jun 22 11:41:54 CEST 2015

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

If I did not misunderstand what this is about, then the problem seem to 
be this:

You are using a DRBD device as the physical volume for a volume group. 
As soon as something changes in that volume group, e.g. you add or 
remove volumes (such as snapshots), the metadata for that volume group 
on the physical volume changes.
That is what you replicate to the peer (the secondary), so all the LVM 
on the peer can see, is data magically changing on its physical volume, 
and that's where the kernel Oops is coming from, because data is not 
supposed to change without the local node knowing about it. This is an 
unsafe scenario unless there is some kind of synchronization in place on 
the LVM level (e.g. "Clustered LVM" aka CLVM -- instead of the normal 
LVM, which is not designed to operate on shared or replicated storage).


On 06/22/2015 11:06 AM, Paul Gideon Dann wrote:
> So no ideas concerning this, then? I've seen the same thing happen on 
> another resource, now. Actually, it doesn't need to be a snapshot: 
> removing any logical volume causes the oops. It doesn't happen for 
> every resource, though.
> [...snip...]
> Paul
> On 16 June 2015 at 11:51, Paul Gideon Dann <pdgiddie at gmail.com 
> <mailto:pdgiddie at gmail.com>> wrote:
>     This is an interesting (though frustrating) issue that I've run
>     into with DRBD+LVM, and having finally exhausted everything I can
>     think of or find myself, I'm hoping the mailing list might be able
>     to offer some help!
>     My setup involves DRBD resources that are backed by LVM LVs, and
>     then formatted as PVs themselves, each forming its own VG.
>     System VG -> Backing LV -> DRBD -> Resource VG -> Resource LVs
>     The problem I'm having happens only for one DRBD resource, and not
>     for any of the others. This is what I do:
>     I create a snapshot of the Resource LV (meaning that the snapshot
>     will also be replicated via DRBD), and everything is fine.
>     However, when I *remove* the snapshot, the *secondary* peer oopses
>     immediately:
>     [...snip...]
>     Cheers,
>     Paul

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.linbit.com/pipermail/drbd-user/attachments/20150622/e812df94/attachment.htm>

More information about the drbd-user mailing list