Just off the top of my head here.
I would expect you need to have no jobs currently running on the node,
so you could could submit a job to the node that sets the node to drain,
does any local things needed, then exits. As part of the EpilogSlurmctld
script, you could check for drained nodes based on some reason (like
'MIG reconfig') and do the head node steps there, with a final bit of
bringing it back online.
Or just do all those steps from a script outside slurm itself, on the
head node. You can use ssh/pdsh to connect to a node and execute things
there while it is out of the mix.
Brian Andrus
On 9/23/2022 7:09 AM, Groner, Rob wrote:
I'm working through how to use the new dynamic node features in order
to take down a particular node, reconfigure it (using nvidia MIG to
change the number of graphic cores available) and give it back to slurm.
I'm at the point where I can take a node out of slurm's control from
the master node (scontrol delete nodename....), make the nvidia-smi
change, and then execute slurmd on the node with the changed
configuration parameters. It then does show up again in the sinfo
output on the master node, with the correct new resources.
What I'm not sure about is...when I want to reconfigure the dynamic
node AGAIN, how do I do that on the target node? I can use "scontrol
delete" again on the scheduler node, but on the dynamic node, slurmd
will still be running. Currently, for testing purposes, I just find
the process ID and kill -9 it. Then I change the node configuration
and execute "slurmd -Z --conf=...." again.
Is there a more elegant way to change the configuration on the dynamic
node than by killing the existing slurmd process and starting it again?
I'll note that I tried doing everything from the master (slurmctld)
node, since there is an option of creating the node there with
"scontrol create" instead of using slurmd on the dynamic node. But
when i tried that, the dynamic node I created showed up in sinfo
output with a ~ next to it (powered off). The dynamic node docs page
online did not mention what, if anything, slurmd was supposed to be
running as on the dynamic node if attempting to handle delete and
create only on the master node.
Thanks.
Rob
