We have implemented that, but we don't do the allocation limits, so the use case is slightly different. It works well, as long as the users "remember" to use it correctly (which I guess you may force/remember them with the allocation). In a nutshell, we have done sacctmgr add qos requeue set Priority=10 PreemptMode=REQUEUE sacctmgr add qos cancel set Priority=10 PreemptMode=CANCEL sacctmgr add qos high set Priority=1000 Preempt=cancel,requeue PreemptMode=cluster sacctmgr add qos max5nodes set priority=50 MaxNodesPerUser=5 PreemptMode=cluster flags=DenyOnLimit sacctmgr modify qos normal set priority=100 sacctmgr modify account default set qos=normal,requeue,cancel,high,max5nodes Then make sure slurm.conf contains PreemptType=preempt/qos PreemptMode=REQUEUE AccountingStorageEnforce=associations,limits,qos The funniest pitfall we encountered is that slurm v23 in our test cluster (which we did not manage to upgrade yet, long story) accepted spaces in slurm.conf but v25 doesn't so we had a space before preempt/qos and that worked fine in the test environment but failed in production for "unknown" reasons until we figured out. On Thu, Jun 4, 2026 at 3:18 PM Steen Lysgaard via slurm-users < slurm-users@lists.schedmd.com> wrote:
Hello,
We have a recurring situation where some users would like to use idle cluster resources on weekends. Their normal CPU limits prevent this, which is generally desirable during the work week to ensure fair sharing.
A pattern we're considering is a special low-priority QOS that allows users to exceed their normal association limits, and that is preemptible by jobs submitted with the normal QOS.
The goal is to let heavy users fill otherwise idle nodes over weekends without impacting smaller users when activity picks up again on Monday. The walltime limit (50 hours) is not something we would like to change.
Has anyone implemented something similar? If so, I'd be interested in hearing about experiences and any pitfalls to this approach.
Thanks, Steen Lysgaard
*Steen Lysgaard* Scientific Software Developer DTU Energy
Mob. +45 51 94 48 86 stly@dtu.dk Agnes Nielsens Vej Building 301 2800 Kgs. Lyngby www.dtu.dk/english
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