[ClusterLabs] Antw: Re: Antw: [EXT] unexpected fenced node and promotion of the new master PAF ‑ postgres

[Jehan-Guillaume de Rorthais]

On Tue, 12 Oct 2021 09:46:04 +0200
"Ulrich Windl" <Ulrich.Windl at rz.uni-regensburg.de> wrote:

> >>> Jehan-Guillaume de Rorthais <jgdr at dalibo.com> schrieb am 12.10.2021 um
> >>> 09:35 in  
> Nachricht <20211012093554.4bb761a2 at firost>:
> > On Tue, 12 Oct 2021 08:42:49 +0200
> > "Ulrich Windl" <Ulrich.Windl at rz.uni-regensburg.de> wrote:
> >   
> ...
> >> "watch cat /proc/meminfo" could be your friend.  
> > 
> > Or even better, make sure you have sysstat or pcp tools family installed and
> > harvesting system metrics. You'll have the full historic of the dirty pages
> > variations during the day/week/month.  
> 
> Actually I think the 10 minute granularity of sysstat (sar) is to coarse to
> learn what's going on, specifically if your node is fenced before the latest
> record is written.

Indeed. You can still set it down to 1min in the crontab if needed. But the
point is to gather a better understanding on the dirties (and many other useful 
metrics) evolution during a long time frame.

You will always loose a small part of information after a fencing. No matter if
your period is 10min, 1min or even 1s.