[ClusterLabs] Antw: [EXT] Correctly stop pacemaker on 2-node cluster with SBD and failed devices?

[Klaus Wenninger]

On Wed, Jun 16, 2021 at 10:47 AM Roger Zhou <zzhou at suse.com> wrote:

>
> On 6/16/21 3:03 PM, Andrei Borzenkov wrote:
>
> >
> >>>
> >>> We thought that access to storage was restored, but one step was
> >>> missing so devices appeared empty.
> >>>
> >>> At this point I tried to restart the pacemaker. But as soon as I
> >>> stopped pacemaker SBD rebooted nodes ‑ which is logical, as quorum was
> >>> now lost.
> >>>
> >>> How to cleanly stop pacemaker in this case and keep nodes up?
> >>
> >> Unconfigurte sbd devices I guess.
> >>
> >
> > Do you have *practical* suggestions on how to do it online in a
> > running pacemaker cluster? Can you explain how it is going to help
> > given that lack of sbd device was not the problem in the first place?
>
> I would translate this issue as "how to gracefully shutdown sbd to
> deregister
> sbd from pacemaker for the whole cluster". Seems no way to do that except
> `systemctl stop corosync`.
>
> With that, to calm down sbd suicide, I'm thinking some tricky steps as
> below
> might help. Well, not sure it fits your situation as the whole.
>
> crm cluster run "systemctl stop pacemaker"
> crm cluster run "systemctl stop corosync"
>
I guess this shouldn't be helpful in this situation.
As I've already tried to explain before shutting down
pacemaker on one of the nodes - if sbd-device can't
be reached - should already be enough for the other
one to suicide.

One - not less ugly than other suggestions here I'm afraid -
thing coming to my mind is to right after stopping pacemaker
dummy-register at the cpg-protocol. If after that you want
to bring down corosync & sbd as well it should be possible
to do that quickly enough - as pcs is otherwise doing with
3+ node clusters.

>
> BR,
> Roger
>
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