[ClusterLabs] Can a two node cluster start resources if only one node is booted?

[Andrei Borzenkov]

On 22.04.2022 16:01, john tillman wrote:
>> On Fri, Apr 22, 2022 at 12:05 PM Tomas Jelinek <tojeline at redhat.com>
>> wrote:
>>>
>>> As discussed in other branches of this thread, you need to figure out
>>> why pacemaker is not starting. Even if one node is not running, corosync
>>> and pacemaker are expected to be able to start on the other node.
>>
>> Well, when trying to reproduce this behavior I configured SBD with a
>> non-existent device and enabled it. If enabled, pacemaker.service
>> Requires sbd.service. sbd.service failed to start and so
>> pacemaker.service was not started either. Just one example.
>>
>> But as long as the only information we have is "nothing suspicious in
>> logs", we can guess until the doomsday. Output of "journalctl -b"
>> immediately after boot would give at least some starting points.
> 
> 
> Thank you all for the responses.  I  shall try to answer your questions
> here.  But I found the problem, I think.  I mean, I made this change and
> now the cluster will start when only one node is booted!
> 
> The drbd service was enabled.  Once I disabled it the cluster would start
> at boot with only one node.
> 
> I took another look through the output of journalctl -b.  I saw this and
> it made me test it:
> 
> systemd[1]: Starting DRBD -- please disable. Unless you are NOT using a
> cluster manager....
> 
> @Klaus - the systemd configuration files showed 2 dependencies before
> pacemaker could start.  one was corosync.  The other was a
> "resource-agents-deps.target", which I could not find.  It looked like an
> option an admin could add.  I'm the admin and I didn't add any.  However,
> this maybe related in someway to pacemaker's relationship to drbd???
> 

If you are an admin, you really should make yourself more familiar with
systemd.

> @Ulrich - the actual pacemaker service was not running.
> 
> @Tomas & Andrei - jounrnalctl did provide the clue.
> 
> Now, can anyone explain why drbd being enabled might keep pacemaker from
> starting? 

Upstream drbd.service has Before=pacemaker.service. If activation of
drbd.service is delayed, so will be pacemaker.


> Would you still care to see the journalctl output?  Maybe
> edited to where systemd starts its logging?
> 

That is really not a pacemaker problem and is better suited for general
systemd troubleshooting resource. But as you have been already
requested, show at least "systemctl status pacemaker.service" and
"systemctl status drbd.service" when pacemaker does not start.