I'm experimenting with slurm powersave and I have several questions. I'm following the guidance from https://slurm.schedmd.com/power_save.html and the great presentation from our own https://slurm.schedmd.com/SLUG23/DTU-SLUG23.pdf
I am running slurm 23.02.3 1) I'm not sure I fully understand ReconfigFlags=KeepPowerSaveSettings The documentations ways that if set, an "scontrol reconfig" command will preserve the current state of SuspendExcNodes, SuspendExcParts and SuspendExcStates. Why would one *NOT* want to preserve that? What would happen if one does not (or does) have this setting? For now I'm using it, assuming that it means "if I run scontrol reconfig" don't shut off nodes that are up because I said so that they should be up in slurm.conf with those three options" --- but I am not clear if that is really what it says. 2) the PDF above says that the problem with nodes in down and drained state is solved in 23.02 but that does not appear to be the case. Before running my experiment, I had $ sinfo -R REASON USER TIMESTAMP NODELIST Not responding root 2023-09-13T13:14:50 node31 ECC memory errors root 2023-08-26T07:21:04 node27 and after it became $ sinfo -R REASON USER TIMESTAMP NODELIST Not responding root 2023-09-13T13:14:50 node31 none Unknown Unknown node27 And that despite having excluded drain'ed nodes as below: --- a/slurm/slurm.conf +++ b/slurm/slurm.conf @@ -140,12 +140,15 @@ SlurmdLogFile=/var/log/slurm/slurmd.log # # # POWER SAVE SUPPORT FOR IDLE NODES (optional) +SuspendProgram=/opt/slurm/poweroff +ResumeProgram=/opt/slurm/poweron +SuspendTimeout=120 +ResumeTimeout=240 #ResumeRate= +SuspendExcNodes=node[13-32]:2 +SuspendExcStates=down,drain,fail,maint,not_responding,reserved +BatchStartTimeout=60 +ReconfigFlags=KeepPowerSaveSettings # not sure if needed: preserve current status when running "scontrol reconfig" -PartitionName=compute512 Default=False Nodes=node[13-32] State=UP DefMemPerCPU=9196 +PartitionName=compute512 Default=False Nodes=node[13-32] State=UP DefMemPerCPU=9196 SuspendTime=600 so probably that's not solved? Anyway, that's a nuisance, not a deal breaker 3) The whole thing does not appear to be working as I intended. My understanding of the "exclude node" above should have meant that slurm should never attempt to shut off more than all idle nodes in that partition minus 2. Instead it shut them off all of them, and then tried to turn them back on: $ sinfo | grep 512 compute512 up infinite 1 alloc# node15 compute512 up infinite 2 idle# node[14,32] compute512 up infinite 3 down~ node[16-17,31] compute512 up infinite 1 drain~ node27 compute512 up infinite 12 idle~ node[18-26,28-30] compute512 up infinite 1 alloc node13 But again this is a minor nuisance which I can live with (especially if it happens only when I "flip the switch"), and I'm mentioning only in case it's a symptom of something else I'm doing wrong. I did try to use both the SuspendExcNodes=node[13-32]:2 syntax as it seem more reasonable to me (compared to the rest of the file, e.g. partitions definition) and the SuspendExcNodes=node[13\-32]:2 as suggested in the slurm powersave documentation. Behavior, exactly identical 4) Most importantly from the output above you may have noticed two nodes (actually three by the time I ran the command below) that slurm deemed down $ sinfo -R REASON USER TIMESTAMP NODELIST Not responding root 2023-09-13T13:14:50 node31 reboot timed out slurm 2023-10-04T14:51:28 node14 reboot timed out slurm 2023-10-04T14:52:28 node15 reboot timed out slurm 2023-10-04T14:49:58 node32 none Unknown Unknown node27 This can't be the case, the nodes are fine, and cannot have timed out while "rebooting", because for now my poweroff and poweron script are identical and literally a simple one-liner bash script doing almost nothing and the log file is populated correctly as I would expect echo "Pretending to $0 the following node(s): $1" >> $log_file 2>&1 So I can confirm slurm invoked the script, but then waited for something (what? starting slurmd?) which failed to occur and marked the node down. When I removed the suspend time from the partition to end the experiment, the other nodes went "magically" in production , without slurm calling my poweron script. Of course the nodes were never powered off, but slurm thought they were, so why it did not have the problem it id with the node which instead intentionally tried to power on? Thanks for any light you can shed on these issues, particularly the last one!
