Hi Tim,
I think the scontrol manual page explains the "scontrol reboot" function
fairly well:
reboot [ASAP] [nextstate={RESUME|DOWN}] [reason=<reason>]
{ALL|<NodeList>}
Reboot the nodes in the system when they become idle using the
RebootProgram as configured in Slurm's slurm.conf file. Each
node will have the "REBOOT" flag added to its node state. After
a node reboots and the slurmd daemon starts up again, the
HealthCheckProgram will run once. Then, the slurmd daemon will
register itself with the slurmctld daemon and the "REBOOT" flag
will be cleared. The node's "DRAIN" state flag will be cleared
if the reboot was "ASAP", nextstate=resume or down. The "ASAP"
option adds the "DRAIN" flag to each node's state, preventing
additional jobs from running on the node so it can be rebooted
and returned to service "As Soon As Possible" (i.e. ASAP).
It seems to be implicitly understood that if nextstate is specified, this
implies setting the "DRAIN" state flag:
The node's "DRAIN" state flag will be cleared if the reboot was "ASAP", nextstate=resume or down.
You can verify the node's DRAIN flag with "scontrol show node <nodename>".
IMHO, if you want nodes to continue accepting new jobs, then nextstate is
irrelevant.
We always use "reboot ASAP" because our cluster is usually so busy that
nodes never become idle if left to themselves :-)
FYI: We regularly make package updates and firmware updates using the
"scontrol reboot asap" method which is explained in this script:
https://github.com/OleHolmNielsen/Slurm_tools/blob/master/nodes/update.sh
Best regards,
Ole,
Ole
On 10/25/23 13:39, Tim Schneider wrote:
Hi Chris,
thanks a lot for your response.
I just realized that I made a mistake in my post. In the section you cite,
the command is supposed to be "scontrol reboot nextstate=RESUME" (without
ASAP).
So to clarify: my problem is that if I type "scontrol reboot
nextstate=RESUME" no new jobs get scheduled anymore until the reboot. On
the other hand, if I type "scontrol reboot", jobs continue to get
scheduled, which is what I want. I just don't understand, why setting
nextstate results in the nodes not accepting jobs anymore.
My usecase is similar to the one you describe. We use the ASAP option when
we install a new image to ensure that from the point of the reinstallation
onwards, all jobs end up on nodes with the new configuration only.
However, in some cases when we do only minor changes to the image
configuration, we prefer to cause as little disruption as possible and
just reinstall the nodes whenever they are idle. Here, being able to set
nextstate=RESUME is useful, since we usually want the nodes to resume
after reinstallation, no matter what their previous state was.
Hope that clears it up and sorry for the confusion!
Best,
tim
On 25.10.23 02:10, Christopher Samuel wrote:
On 10/24/23 12:39, Tim Schneider wrote:
Now my issue is that when I run "scontrol reboot ASAP nextstate=RESUME
<node>", the node goes in "mix@" state (not drain), but no new jobs get
scheduled until the node reboots. Essentially I get draining behavior,
even though the node's state is not "drain". Note that this behavior is
caused by "nextstate=RESUME"; if I leave that away, jobs get scheduled
as expected. Does anyone have an idea why that could be?
The intent of the "ASAP` flag for "scontrol reboot" is to not let any
more jobs onto a node until it has rebooted.
IIRC that was from work we sponsored, the idea being that (for how our
nodes are managed) we would build new images with the latest software
stack, test them on a separate test system and then once happy bring
them over to the production system and do an "scontrol reboot ASAP
nextstate=resume reason=... $NODES" to ensure that from that point
onwards no new jobs would start in the old software configuration, only
the new one.
Also slurmctld would know that these nodes are due to come back in
"ResumeTimeout" seconds after the reboot is issued and so could plan for
them as part of scheduling large jobs, rather than thinking there was no
way it could do so and letting lots of smaller jobs get in the way.
