[ClusterLabs] Antw: [EXT] Re: Possible timing bug in SLES15

[Ulrich Windl]

>>> Roger Zhou via Users <users at clusterlabs.org> schrieb am 12.10.2021 um 09:55
in
Nachricht <d4b21140-4a96-d882-73f0-1060bd398d5e at suse.com>:

...
>> # Time syncs can make the clock jump backward, which messes with logging
>> # and failure timestamps, so wait until it's done.
>> After=time‑sync.target
>> ...
>> 
>> Oct 05 14:58:10 h16 pacemakerd[6974]:  notice: Starting Pacemaker 
> 2.0.4+20200616.2deceaa3a‑3.9.1
>> But still it does not "Require" time‑sync.target...
>> 
> 
> Actually `After=` is more strict dependency than `Require=`.

>From discussions in the systemd development list there is hardly a scenario
where after without require makes sense, because (as I understood it) "After"
only has an effect if both units are started in the same "transaction". The way
I understood it, it would mean that if you start pacemaker manuall and your
clock is not in-sync, it would start pacemaker anyway.
I may be wrong, though.
Maybe a counter-argument is that pacemaker might stop if the time in not in
sync (although I believe a dependency on NTP would be bad, but time-sync is
probably OK).

> 
>> Doesn't corosync need synchronized clocks?
> 
> Seems good to have, but low priority.

Well at least when comparing log timestamps it seems useful if all nodes have
the same time.

Regards,
Ulrich