Reservations

Resources reservations

Slurm gives the possibility to reserve one or more compute nodes exclusively for a specific user or group of users. A reservation ensures that the designated node (or nodes) are dedicated solely to the reservation holder’s tasks and are not shared with other users during the reserved period. This feature allows users to plan the execution of future workloads, and accommodates cluster users with special needs beyond the batch system (eg latency measurement scenarios).

Requesting a Reservation

To request a reservation for nodes, please use to the Request Reservation form. You can request a reservation for an entire compute node (or a group of nodes) if you have contributed this (or these) nodes to the cluster and you have special needs that needs to be accommodated.

General guidelines for reservations’ requests:

• You can be granted a reservation only on nodes from a partition that is contributed by your group (See Partitions to check the name of the partition contributed by your group, and System specifications for a listing of available nodes and their features).
• Please ask for the least amount of resources you need as to minimize impact on other users.
• Plan ahead and request your reservation as soon as possible: Reservations usually ignore running jobs, so any running job on the machine(s) you request will continue to run when the reservation starts. While jobs from other users will not start on the reserved node(s), the resources in use by an already running job at the start time of the reservation will not be available in the reservation until this running job ends. The earlier ahead you request resources, the easier it is to allocate the requested resources.

Using reservations

Once your reservation request is approved and a reservation is placed on the system, you can run your jobs in the reservation by specifying --qos=reservation along with the following directives to your slurm commands: --reservation=<name> and --partition=<partition>. For example, to submit the job job.sbatch to a reservation named icra_iv on the cor1 node on the cor partition use:

$ sbatch --qos=reservation --reservation=icra_iv --partition=cor job.sbatch

Alternatively, it is possible to add the following lines to the job.sbatch file, and submitting this file as usual:

#SBATCH --qos=reservation
#SBATCH --reservation=icra_iv
#SBATCH --partition=cor

$ srun --qos=reservation --reservation=<reservation_name> --partition=<partition_name> <some_script.sh>

To make use of an existing reservation you have to specify --qos=reservation and --reservation=<reservation-name> in your sbatch script.

Viewing reservations

To view all active and future reservations run the scontrol command as follows:

$ scontrol show reservations
ReservationName=icra_iv StartTime=2023-09-09T00:00:00 EndTime=2023-09-16T00:00:00 Duration=7-00:00:00
   Nodes=cor1 NodeCnt=1 CoreCnt=32 Features=(null) PartitionName=cor Flags=
   TRES=cpu=64
   Users=(null) Groups=(null) Accounts=3me-cor Licenses=(null) State=ACTIVE BurstBuffer=(null) Watts=n/a
   MaxStartDelay=(null)

ReservationName=maintenance weekend 2023-10-14 StartTime=2023-10-13T20:00:00 EndTime=2023-10-16T09:00:00 Duration=2-13:00:00
   Nodes=3dgi[1-2],100plus,awi[01-26],cor1,gpu[01-11],grs[1-4],influ[1-6],insy[11-12,14-16],tbm5,wis1 NodeCnt=58 CoreCnt=2000 Features=(null) PartitionName=(null) Flags=MAINT,IGNORE_JOBS,SPEC_NODES,ALL_NODES
   TRES=cpu=4000
   Users=root Groups=(null) Accounts=(null) Licenses=(null) State=INACTIVE BurstBuffer=(null) Watts=n/a
   MaxStartDelay=(null)