[Pacemaker] resource monitor priority - timeout on high load

[Dejan Muhamedagic]

Hi,

On Mon, Oct 05, 2015 at 12:53:25PM -0500, Radoslaw Garbacz wrote:
> Hi,
> 
> I have a situation, when resource monitor operations timeout on system high
> load.
> 
> One thing to do is to increase timeouts, but there can always be load, at
> which the timeout event would happen, and on the other hand too long
> timeouts would not be very useful,

Why do you think so? Did you see actual failures due to a
timeout, i.e. a process just hanging in limbo?

> so I would like to increase the priority
> of monitoring processes (GNU Linux), but I do not want to be too broad.

If that could make the server a bit bigger too ;-)

Seriously, IMO you have two options: either add more resources
(as in hardware) or increase the monitor timeouts.

Thanks,

Dejan

> So my question is, which pacemaker process should I target to ensure timely
> monitoring operations, or maybe even there is a pacemaker configuration
> parameter, which would help in such a case.
> 
> I know for sure, that agents finish they monitoring requests on time, and
> the timeout is due to high load. I have several agents, so I will provide
> just some details to illustrate the case:
> - timeout: ~60s
> - interval: ~60s
> - normal (low load) monitor request time: 0.2s
> - high load monitor request time: 8s - when pacemaker reports resource
> operation timeout
> 
> 
> Thanks,
> 
> -- 
> Best Regards,
> 
> Radoslaw Garbacz
> XtremeData Incorporation

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