[Linux-HA] OS process priority of monitor action

[Alan Robertson]

Andreas Mock wrote:
> Hi all,
> 
> after many days without dopey questions from me I'm back: ;-)
> All questions concerning HAv2 (2.1.2-x).
> 
> Is the resource agent action 'monitor' done with a higher
> OS process priority?
> 
> I'm asking about that, because we had the following phenomena:
> 1) (Very) High load on server
> 2) Monitor action initiated
> 3) Monitor action timed out because of high load
> 4) Stopping of resource initiated because of resource failover
> 5) Stop action timed out
> 6) Stonith of node
> 
> Conclusion: Monitoring which is a nice feature can bring all
> services on that node down if the server is doing what it has to do:
> Working hard.
> 
> Our solution: (Very) long timeout values for monitoring actions.
> 
> Is this the only solution? Would it be feasible to let the monitor
> action of the RA run with higher priority? Have I forgot something?

I believe that you have hit on the only really good general solution.

Raising the priority won't raise I/O priority or make the monitor and 
stop actions stay locked in memory so that they don't get paged in or 
out behind a huge I/O queue.


-- 
     Alan Robertson <alanr at unix.sh>

"Openness is the foundation and preservative of friendship...  Let me 
claim from you at all times your undisguised opinions." - William 
Wilberforce