Users can request a scheduled reservation of machine resources if their jobs have special needs that cannot be accommodated through the regular batch system. A reservation brings some portion of the machine to a specific user or project for an agreed upon duration. Typically this is used for interactive debugging at scale or real time processing linked to some experiment or event.
It is not intended to be used to guarantee fast throughput for production runs.
For normal batch jobs, charging against a project's allocation is done on a per job basis. For scheduled reservations the entire block of reserved time is charged regardless of the number of nodes used or time spent running jobs.
Requesting a reservation¶
To reserve compute nodes, a request must be sent in with at least 72 hours notice. Please ask for the least amount of resources you need and try to schedule reservations so as to minimize impact on other users. It is also recommended that reservations be scheduled to start during NERSC business hours to ensure availability of staff in case any issues arise.
Cancellation of a reservation must be done with a minimum of 72 hours notice as well. If you do not receive a confirmation that your cancellation was received and it is less than 72 hours until your start time you must contact NERSC operations via 1-800-666-3772 (or 1-510-486-8600) menu option 1 to confirm.
Using a reservation¶
Once your reservation request is approved and a reservation is placed on the system use the
nersc$ sbatch --reservation=<reservation_name>
nersc$ salloc --reservation=<reservation_name>
#SBATCH --reservation=<reservation_name> to your job script.
It is possible to submit jobs to a reservation once it is created - jobs will start immediately when the reservation is available.
KNL mode changes¶
KNL reboots can take up to 1 hour.
KNL nodes are configured as quad,cache by default. If you have requested a reservation with a different mode you will be responsible for rebooting the nodes into the proper mode and should account for this in your request.
Additional demonstration of need may be required for large scale reservations requesting reboots as system administrators are needed to assist in the reboot.
It is recommended to submit a "test" job at the start of your reservation to reboot the nodes.
cori$ sbatch -C knl,quad,flat --nodes=<size_of_reservation> --qos=regular --reservation=<reservation_name> --wrap="hostname"
If you forget to put the correct
-C option on all of your jobs you may lose 2 hours of your reservation to reboots.
Ending a reservation¶
All running jobs under a reservation will be terminated when the reservation ends. If you complete the planned computations before the reservation ends, please call NERSC operations at 1-800-666-3772 (or 1-510-486-8600) menu option 1 to cancel the reservation.