[slurm-users] Transparently assign different walltime limit to a group of nodes ?

[Cyrus Proctor]

Hi Jens,

Check out https://slurm.schedmd.com/reservations.html specifically the " 
Reservations Floating Through Time" section. In your case, set a 
walltime of 14 days for your partition that contains n[01-10]. Then, 
create a floating reservation on node n[06-10] for n + 1 day where "n" 
is always evaluated as now.

If you wish to allow the user more control, then specify a "Feature" in 
slurm.conf for you nodes. Something like:
NodeName=n[01-05] Sockets=1 CoresPerSocket=48 ThreadsPerCore=2 
State=UNKNOWN Feature=long
NodeName=n[06-10] Sockets=1 CoresPerSocket=48 ThreadsPerCore=2 
State=UNKNOWN Feature=short

The feature is an arbitrary string that the admin sets. Then a user 
could specify in their submission as something like:
sbatch --constraint="long|short" batch.slurm

Best,
Cyrus

On 08/13/2018 08:28 AM, Loris Bennett wrote:
> Hi Jens,
>
> Jens Dreger <jens.dreger at physik.fu-berlin.de> writes:
>
>> Hi everyone!
>>
>> Is it possible to transparently assign different walltime limits
>> to nodes without forcing users to specify partitions when submitting
>> jobs?
>>
>> Example: let's say I have 10 nodes. Nodes n01-n05 should be available
>> for jobs with a walltime up to 14 days, while n06-n10 should only
>> be used for jobs with a walltime limit less then 1 day. Then as long
>> as nodes n06-n10 have free resources, jobs with walltime <1day should
>> be scheduled to these nodes. If n06-n10 are full, jobs with walltime
>> <1day should start on n01-n05. Users should not have to specify
>> partitions.
>>
>> Would this even be possible to do with just one partition much
>> like nodes with different memory size using weights to fill nodes
>> with less memoery first?
>>
>> Background of this question is that it would be helpfull to be able
>> to lower the walltime for a rack of nodes, e.g. when adding this rack
>> to an existing cluster in order to be able to easily shut down just
>> this rack after one day in case of instabilities. Much like adding
>> N nodes to a cluster without changing anything else and have only
>> jobs with walltime <1day on thiese nodes in the beginning.
> If you just want to reduce the allowed wall-time for a given rack, can't
> you just use a maintenance reservation for the appropriate set of nodes?
>
> Cheers,
>
> Loris
>

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