[slurm-users] Question about using topology/tree

[Antonio Lara]

Hello,

I'm trying to use the topology/tree plugin to isolate nodes in different
"groups", so that jobs can be allocated only on nodes belonging to one
such group, and not in nodes from other groups. I think I'm missing
something, because Slurm doesn't seem to take this topology into
consideration. Hopefully someone can spot what I'm doing wrong. So far
I'm trying to separate a 3 node cluster into two groups, using two
switches. I have created a topology.conf file, and placed it in the etc
directory of the slurm installation path. This file contains these two
lines:

SwitchName=s0 Nodes=node1,node2
SwitchName=s1 Nodes=node3

I also tried adding a third switch that contains the s0 and s1 switches,
but it didn't solve anything.

Then, I have enabled the use of the topology/tree plugin with this line
in slurm.conf:

TopologyPlugin=topology/tree

And finally these changes are taken into consideration with:

scontrol reconfigure

Then, I would expect that launching a job that requires 2 nodes would be
run on node1 and node2 only, since these two shoud be grouped under the
switch "s0", but it runs on node1 and node3, ignoring the topology, when
I send a command like this:

sbatch -A molecules_serv -p cc -N 2 -n 4 --switches=1 ./script1

Maybe I'm not understanding correctly what the --switches flag does, but
I think it should only consider nodes that are under 1 switch, and among
those, use those that can at the same time fullfill the other
requirements, like the number of nodes or tasks. Therefore I would
expect it to only run the job in node1 and node2 in parallel, but not
node3.

Any ideas?

Thank you very much for your help

Antonio

[Antonio Lara]

Hi again,

Also, if I write the nodes names wrong in topology.conf (that is, nodes
that are not specified in slurm.conf, in the line describing the
partition, under "Nodes="), when I do scontrol reconfigure, there is no
complaint or messages in the logs, so it seems like the topology.conf
file might not be being processed (it has permissions 644 and is in the
same directory as slurm.conf), but "scontrol show config" shows that the
topology/tree plugin is loaded correctly.

Thank you

Best regards

Antonio


El 23/05/18 a las 11:04, Antonio Lara escribió:

[Antonio Lara]

Ok, never mind, I think I got it, it seems that scontrol reconfigure was
not enough, I also had to restart the slurm daemons and it seems to work
now.

Regards!


El 23/05/18 a las 13:00, Antonio Lara escribió: