On Mon, Mar 18, 2019 at 4:15 PM levin <levin(a)mydream.com.hk> wrote:
Hi Sahina,
My cluster did not enabled fencing, is somewhere I can disable restart policy from vdsm
completely? So I can observe this case next time, and giving a fist investigation on
unresponsive node.
+Martin Perina - do you know if this is possible?
> Regards,
> Levin
>
>
> On 18/3/2019, 17:40, "Sahina Bose" <sabose(a)redhat.com> wrote:
>
> On Sun, Mar 17, 2019 at 12:56 PM <levin(a)mydream.com.hk> wrote:
> >
> > Hi, I had experience two time of 3-node hyper-converged 4.2.8 ovirt cluster
total outage due to vdsm reactivate the unresponsive node, and cause the multiple
glusterfs daemon restart. As a result, all VM was paused and some of disk image was
corrupted.
> >
> > At the very beginning, one of the ovirt node was overloaded due to high
memory and CPU, the hosted-engine have trouble to collect status from vdsm and mark it as
unresponsive and it start migrate the workload to healthy node. However, when it start
migrate, second ovirt node being unresponsive where vdsm try reactivate the 1st
unresponsive node and restart it's glusterd. So the gluster domain was acquiring the
quorum and waiting for timeout.
> >
> > If 1st node reactivation is success and every other node can survive the
timeout, it will be an idea case. Unfortunately, the second node cannot pick up the VM
being migrated due to gluster I/O timeout, so second node at that moment was marked as
unresponsive, and so on... vdsm is restarting the glusterd on the second node which cause
disaster. All node are racing on gluster volume self-healing, and i can't mark the
cluster as maintenance mode as well. What I can do is try to resume the paused VM via
virsh and issue shutdown for each domain, also hard shutdown for un-resumable VM.
> >
> > After number of VM shutdown and wait the gluster healing completed, the
cluster state back to normal, and I try to start the VM being manually stopped, most of
them can be started normally, but number of VM was crashed or un-startable, instantly I
found the image files of un-startable VM was owned by root(can't explain why), and can
be restarted after chmod. Two of them still cannot start with "bad volume
specification" error. One of them can start to boot loader, but the LVM metadata were
lost.
> >
> > The impact was huge when vdsm restart the glusterd without human invention.
>
> Is this even with the fencing policies set for ensuring gluster quorum
> is not lost?
>
> There are 2 policies that you need to enable at the cluster level -
> Skip fencing if Gluster bricks are UP
> Skip fencing if Gluster quorum not met
>
>
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