[slurm-users] Topology configuration questions:

[Nicholas McCollum]

I recommend putting heterogeneous node types each into their own patition to keep jobs from spanning multiple node types.  You can also set QoS's for different partitions and make a job in that QoS only able to be scheduled on nodes=1.  You could also accomplished this with a partition config in your slurm.conf... or use the job_submit.lua plugin to capture jobs submitted to that partition and change max nodes =1.
There's a lot of easy ways to skin that cat.

I personally like using the submit all jobs to all partitions plugin and having users constrain to specific types of nodes using the --constraint=whatever flag.


Nicholas McCollum
Alabama Supercomputer Authority
________________________________
From: "Fulcomer, Samuel" <samuel_fulcomer at brown.edu>
Sent: Thursday, January 17, 2019 5:58 PM
To: Slurm User Community List
Subject: Re: [slurm-users] Topology configuration questions:

We use topology.conf to segregate architectures (Sandy->Skylake), and also to isolate individual nodes with 1Gb/s Ethernet rather than IB (older GPU nodes with deprecated IB cards). In the latter case, topology.conf had a switch entry for each node.

It used to be the case that SLURM was unhappy with nodes defined in slurm.conf not appearing in topology.conf. This may have changed....

On Thu, Jan 17, 2019 at 6:37 PM Ryan Novosielski <novosirj at rutgers.edu<mailto:novosirj at rutgers.edu>> wrote:
I don’t actually know the answer to this one, but we have it provisioned to all nodes.

Note that if you care about node weights (eg. NodeName=whatever001 Weight=2, etc. in slurm.conf), using the topology function will disable it. I believe I was promised a warning about that in the future in a conversation with SchedMD.

> On Jan 17, 2019, at 4:52 PM, Prentice Bisbal <pbisbal at pppl.gov<mailto:pbisbal at pppl.gov>> wrote:
>
> And a follow-up question: Does topology.conf need to be on all the nodes, or just the slurm controller? It's not clear from that web page. I would assume only the controller needs it.
>
> Prentice
>
> On 1/17/19 4:49 PM, Prentice Bisbal wrote:
>> From https://slurm.schedmd.com/topology.html:
>>
>>> Note that compute nodes on switches that lack a common parent switch can be used, but no job will span leaf switches without a common parent (unless the TopologyParam=TopoOptional option is used). For example, it is legal to remove the line "SwitchName=s4 Switches=s[0-3]" from the above topology.conf file. In that case, no job will span more than four compute nodes on any single leaf switch. This configuration can be useful if one wants to schedule multiple phyisical clusters as a single logical cluster under the control of a single slurmctld daemon.
>>
>> My current environment falls into the category of multiple physical clusters being treated as a single logical cluster under the control of a single slurmctld daemon. At least, that's my goal.
>>
>> In my environment, I have 2 "clusters" connected by their own separate IB fabrics, and one "cluster" connected with 10 GbE. I have a fourth cluster connected with only 1GbE. For this 4th cluster, we don't want jobs to span nodes, due to the slow performance of 1 GbE. (This cluster is intended for serial and low-core count parallel jobs) If I just leave those nodes out of the topology.conf file, will that have the desired affect of not allocating multi-node jobs to those nodes, or will it result in an error of some sort?
>>
>

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