[ClusterLabs] SLES12 SP4: update_cib_stonith_devices_v2 nonsense "Watchdog will be used via SBD if fencing is required"

[Ken Gaillot]

On Wed, 2019-10-23 at 15:53 +0300, Andrei Borzenkov wrote:
> 23.10.2019 13:35, Ulrich Windl пишет:
> > Hi!
> > 
> > In SLES12 SP4 I'm kind of annoyed due to repeating messages
> > "unpack_config:    Watchdog will be used via SBD if fencing is
> > required".

It is annoying, but it's a side effect of pacemaker's atomicity.
Whenever pacemaker's scheduler runs, it bases its actions on a snapshot
of the cluster at that moment. Each such run is completely independent
of all other runs, so in effect, it sees everything in the
configuration as "new". Any configuration-related messages thus get
logged every time the scheduler runs.

We did introduce a squelch on this in 1.1.18 / 2.0.0. For certain
messages, we can mark them as "log once". Those will only be logged
once during the lifetime of the scheduler daemon (i.e. once per cluster
restart). We use this almost exclusively for deprecation warnings,
because it's better to have annoying repetition than missing
information that might be relevant to a problem investigation.

> > While examining another problem, I found this sequence:
> > * Some unrelated resource was moved (migrated)
> > * stonith-ng:     info: update_cib_stonith_devices_v2:    Updating
> > device list from the cib: create constraints
> > 
> > (at that point I'm expecting that there was NO update related to
> > SBD devices)

That one annoys me, too. I hope to get rid of it one day but there's
just too much higher priority work to do. It's a similar situation to
the scheduler: whenever the CIB changes at all, the fencer updates its
view of the stonith device list, and logs such a message regardless of
whether anything actually changed or not.

> > * stonith-ng:     info: cib_devices_update:       Updating devices
> > to version 2.35.0
> > * stonith-ng:   notice: unpack_config:    Watchdog will be used via
> > SBD if fencing is required
> > * cib:     info: cib_file_write_with_digest:       Wrote version
> > 2.35.0 of the CIB to disk (digest:
> > 8e3625f4ef74b6fe6c6429757023b7e9)
> > 
> > I mean: I know that SBD will use the watchdog for fencing if
> > everything else fails, but why is this message logged so many
> > times?
> > 
> 
> This message is also misleading. Pacemaker will actually use watchdog
> self-fencing only if stonith-watchdog-timeout is not zero. And zero
> is
> default.

Good point, I'll update the message accordingly.
-- 
Ken Gaillot <kgaillot at redhat.com>