[slurm-users] [External] Hibernating a whole cluster

Tue Feb 7 14:45:57 UTC 2023

Hi Analabha,

Yes, unfortunately for your needs, I expect a time limited reservation along my suggestion would not accept jobs that would be scheduled to end outside of the reservations availability times. I'd suggest looking at check-pointing in this case, e.g. with DMTCP: Distributed MultiThreaded Checkpointing, http://dmtcp.sourceforge.net/. That could allow jobs to have their state saved and then re-loaded when they are started again.

Best

Sean

---
Sean McGrath
Senior Systems Administrator, IT Services

________________________________
From: slurm-users <slurm-users-bounces at lists.schedmd.com> on behalf of Analabha Roy <hariseldon99 at gmail.com>
Sent: Tuesday 7 February 2023 12:14
To: Slurm User Community List <slurm-users at lists.schedmd.com>
Subject: Re: [slurm-users] [External] Hibernating a whole cluster

Hi Sean,

Thanks for your awesome suggestion! I'm going through the reservation docs now. At first glance, it seems like a daily reservation would turn down jobs that are too big for the reservation. It'd be nice if
slurm could suspend (in the manner of 'scontrol suspend') jobs during reserved downtime and resume them after. That way, folks can submit large jobs without having to worry about the downtimes. Perhaps the FLEX option in reservations can accomplish this somehow?

I suppose that I can do it using a shell script iterator and a cron job, but that seems like an ugly hack. I was hoping if there is a way to config this in slurm itself?

AR

On Tue, 7 Feb 2023 at 16:06, Sean Mc Grath <smcgrat at tcd.ie<mailto:smcgrat at tcd.ie>> wrote:
Hi Analabha,

Could you do something like create a daily reservation for 8 hours that starts at 9am, or whatever times work for you like the following untested command:

scontrol create reservation starttime=09:00:00 duration=8:00:00 nodecnt=1 flags=daily ReservationName=daily

Daily option at https://slurm.schedmd.com/scontrol.html#OPT_DAILY

Some more possible helpful documentation at https://slurm.schedmd.com/reservations.html, search for "daily".

My idea being that jobs can only run in that reservation, (that would have to be configured separately, not sure how from the top of my head), which is only active during the times you want the node to be working. So the cronjob that hibernates/shuts it down will do so when there are no jobs running. At least in theory.

Hope that helps.

Sean

---
Sean McGrath
Senior Systems Administrator, IT Services

________________________________
From: slurm-users <slurm-users-bounces at lists.schedmd.com<mailto:slurm-users-bounces at lists.schedmd.com>> on behalf of Analabha Roy <hariseldon99 at gmail.com<mailto:hariseldon99 at gmail.com>>
Sent: Tuesday 7 February 2023 10:05
To: Slurm User Community List <slurm-users at lists.schedmd.com<mailto:slurm-users at lists.schedmd.com>>
Subject: Re: [slurm-users] [External] Hibernating a whole cluster

Hi,

Thanks. I had read the Slurm Power Saving Guide before. I believe the configs enable slurmctld to check other nodes for idleness and suspend/resume them. Slurmctld must run on a separate, always-on server for this to work, right?

My issue might be a little different. I literally have only one node that runs everything: slurmctld, slurmd, slurmdbd, everything.

This node must be set to "sudo systemctl hibernate"after business hours, regardless of whether jobs are queued or running. The next business day, it can be switched on manually.

systemctl hibernate is supposed to save the entire run state of the sole node to swap and poweroff. When powered on again, it should restore everything to its previous running state.

When the job queue is empty, this works well. I'm not sure how well this hibernate/resume will work with running jobs and would appreciate any suggestions or insights.

AR

On Tue, 7 Feb 2023 at 01:39, Florian Zillner <fzillner at lenovo.com<mailto:fzillner at lenovo.com>> wrote:
Hi,

follow this guide: https://slurm.schedmd.com/power_save.html

Create poweroff / poweron scripts and configure slurm to do the poweroff after X minutes. Works well for us. Make sure to set an appropriate time (ResumeTimeout) to allow the node to come back to service.
Note that we did not achieve good power saving with suspending the nodes, powering them off and on saves way more power. The downside is it takes ~ 5 mins to resume (= power on) the nodes when needed.

Cheers,
Florian
________________________________
From: slurm-users <slurm-users-bounces at lists.schedmd.com<mailto:slurm-users-bounces at lists.schedmd.com>> on behalf of Analabha Roy <hariseldon99 at gmail.com<mailto:hariseldon99 at gmail.com>>
Sent: Monday, 6 February 2023 18:21
To: slurm-users at lists.schedmd.com<mailto:slurm-users at lists.schedmd.com> <slurm-users at lists.schedmd.com<mailto:slurm-users at lists.schedmd.com>>
Subject: [External] [slurm-users] Hibernating a whole cluster

Hi,

I've just finished  setup of a single node "cluster" with slurm on ubuntu 20.04. Infrastructural limitations  prevent me from running it 24/7, and it's only powered on during business hours.

Currently, I have a cron job running that hibernates that sole node before closing time.

The hibernation is done with standard systemd, and hibernates to the swap partition.

 I have not run any lengthy slurm jobs on it yet. Before I do, can I get some thoughts on a couple of things?

If it hibernated when slurm still had jobs running/queued, would they resume properly when the machine powers back on?

Note that my swap space is bigger than my  RAM.

Is it necessary to perhaps setup a pre-hibernate script for systemd to  iterate scontrol to suspend all the jobs before hibernating and resume them post-resume?

What about the wall times? I'm uessing that slurm will count the downtime as elapsed for each job. Is there a way to config this, or is the only alternative a post-hibernate script that iteratively updates the wall times of the running jobs using scontrol again?

Thanks for your attention.
Regards
AR

--
Analabha Roy
Assistant Professor
Department of Physics<http://www.buruniv.ac.in/academics/department/physics>
The University of Burdwan<http://www.buruniv.ac.in/>
Golapbag Campus, Barddhaman 713104
West Bengal, India
Emails: daneel at utexas.edu<mailto:daneel at utexas.edu>, aroy at phys.buruniv.ac.in<mailto:aroy at phys.buruniv.ac.in>, hariseldon99 at gmail.com<mailto:hariseldon99 at gmail.com>
Webpage: http://www.ph.utexas.edu/~daneel/

--
Analabha Roy
Assistant Professor
Department of Physics<http://www.buruniv.ac.in/academics/department/physics>
The University of Burdwan<http://www.buruniv.ac.in/>
Golapbag Campus, Barddhaman 713104
West Bengal, India
Emails: daneel at utexas.edu<mailto:daneel at utexas.edu>, aroy at phys.buruniv.ac.in<mailto:aroy at phys.buruniv.ac.in>, hariseldon99 at gmail.com<mailto:hariseldon99 at gmail.com>
Webpage: http://www.ph.utexas.edu/~daneel/
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