[slurm-users] slurm node weights

[Merlin Hartley]

I believe this is so that small jobs will naturally go on older, slower nodes first - leaving the bigger,better ones for jobs that actually need them.


Merlin
--
Merlin Hartley
IT Support Engineer
MRC Mitochondrial Biology Unit
University of Cambridge
Cambridge, CB2 0XY
United Kingdom

> On 5 Sep 2019, at 16:48, Douglas Duckworth <dod2014 at med.cornell.edu> wrote:
> 
> Hello
> 
> We added some newer Epyc nodes, with NVMe scratch, to our cluster and so want jobs to run on these over others.  So we added "Weight=100" to the older nodes and left the new ones blank.  So indeed, ceteris paribus, srun reveals that the faster nodes will accept jobs over older ones.
> 
> We have the desired outcome though I am a bit confused by two statements in the manpage <https://slurm.schedmd.com/slurm.conf.html> that seem to be contradictory:
> 
> "All things being equal, jobs will be allocated the nodes with the lowest weight which satisfies their requirements."
> 
> "...larger weights should be assigned to nodes with more processors, memory, disk space, higher processor speed, etc."
> 
> 100 is larger than 1 and we do see jobs preferring the new nodes which have the default weight of 1.  Yet we're also told to assign larger weights to faster nodes?
> 
> Thanks!
> Doug
> 
> -- 
> Thanks,
> 
> Douglas Duckworth, MSc, LFCS
> HPC System Administrator
> Scientific Computing Unit <https://scu.med.cornell.edu/>
> Weill Cornell Medicine"
> E: doug at med.cornell.edu <mailto:doug at med.cornell.edu>
> O: 212-746-6305
> F: 212-746-8690

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