[Pacemaker] drbd-xen and fencing

Andrew Beekhof andrew at beekhof.net
Mon Nov 15 02:08:40 EST 2010

Don't use init.d/drbd, use the ocf script that comes with the drbd packages

On Thu, Nov 11, 2010 at 2:19 PM, Vadym Chepkov <vchepkov at gmail.com> wrote:
> Hi,
> I posted a less elaborate version of this question to drbd mail-list, but,
> unfortunately, didn't get a reply,
> maybe audience of this list has more experience.
> I am trying to make xen live migration to work reliably, but wasn't
> successful so far.
> Here is the problem.
> In a cluster configuration I have two type of resources - file systems on
> drbd, with explicit drbd resources configuration and
> Xen resources with implicit, using drbd-xen block device helper. For the
> former everything works great, but the latter doesn't work quite well.
> In order for helper script to work, drbd module has to be loaded and
> underlying resources up. So I have to start init.d/drbd script.
> I can't make it an lsb cluster resource, because stop will be disastrous for
> file system resources. Enable it in startup sequence breaks
> /usr/lib/drbd/crm-unfence-peer.sh, because cluster stack is not completely
> up by the time drbd script finishes, and there is no way to configure only
> specific resources that need to be initialized.
> Also, I can't find a way fence Xen resource. I tried fence-peer
> "/usr/lib/drbd/crm-fence-peer.sh -i xen_vsvn",
> where xen_svn is the name of Xen primitive, but it doesn't work,
> so there is a danger of starting Xen VM on an out-of-date node. Then there
> is no way of monitoring underlying drbd resources too.
> I thought of adding underlying drbd resource explicitly in the cluster, but
> I can't figure out what would be the configuration
> for "this resource can be master on both nodes, but if just on one, it's
> fine too".
> allow-two-primaries has to be allowed for live migration and at the time of
> migration resources are primary on both nodes, but when migration finishes,
> it's again primary/slave. But if I configure drbd resource in the cluster
> with meta master-max="2" master-node-max="1",
> cluster insists on having them both primary all the time.
> Hope I didn't bore you to death and there is an elegant solution for
> this conundrum :)
> Thank you,
> Vadym
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