[ClusterLabs] Antw: Placing resource based on least load on a node

Ulrich Windl Ulrich.Windl at rz.uni-regensburg.de
Tue Nov 20 02:06:11 EST 2018

>>> Bernd <bernd at kroenchenstadt.de> schrieb am 20.11.2018 um 07:21 in Nachricht
<dbae607c63168d4e14584abfba0b4b1b at kroenchenstadt.de>:
> Hi,
> I'd like to run a certain bunch of cronjobs from time to time on the 
> cluster node (four node cluster) that has the lowest load of all four 
> nodes.
> The parameters wanted for this system yet to build are
> * automatic placement on one of the four nodes (i.e., that with the 
> lowest load)
> * in case a node fails, automatically removed from the cluster
> * it must only exist a single entity of the cronjob entity running
> so this really screams for pacemakter being used as foundation.
> However, I'm not sure how to implement the "put onto node with least 
> load" part. I was thinking to use Node Attributes for that, but I didn't 
> find any solution "out of the box" for this. Furthermore, as load is a 
> highly volatile value, how can one make sure that all cronjobs are run 
> to the end without being moved to a node that possibly meanwhile got a 
> lower load than the one executing the jobs?


Actually I think the last one is the easiest (assuming the cron jobs do not need any resources that are moved): Once a cron job is started, it will run until it ends, whether it's crontab has been moved or not.

Despite of that I think cluster software is not ideal when you actually need load-balancing software.


> Thanks,
> Bernd
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