1. OAR : a batch scheduler Bruno.Bzeznik@imag.fr Grenoble University LIG (Mescal Team)

3. OAR : a batch scheduler A batch scheduler is a software for sharing computing resources between users. It places jobs on the cluster's resources depending on the time they have been submitted, the load of the nodes and some constraints

4. OAR : a batch scheduler OAR is OpenSource, distributed under the GPL license It is written in Perl. It uses SSH as the communication model and sudo as the security model. An SQL database is used as the core model.

5. OAR main features - Batch and Interactive jobs - Admission rules - Walltime - Matching of resources (job/node properties) - Hold and resume jobs - Multi-schedulers support (simple fifo and fifo with matching) - Multi-queues with priority - Best-effort queues (for exploiting idle resources) - Check compute nodes before launching - Epilogue/Prologue scripts - No Daemon on compute nodes - Dynamic insertion/deletion of compute node - Logging - Backfiling - First-Fit Scheduler with matching resource (very soon) - Fairsharing - Advance Reservation - Cpuset feature used to optimize, clean and control access to nodes

6. OAR usage A command to watch resources: 'oarnodes'

7. OAR usage A command to watch jobs: 'oarstat'

8. OAR usage A command to submit jobs: 'oarsub'

9. OAR usage ● oarsub examples: – # I want 2 nodes: oarsub -l /nodes=2 “sleep 300” – # I want 4 cpus, with an interactive shell, for 4 hours: oarsub -l /cpu=4,walltime=4 -I – # I want 4 cpus, but 1 per node: oarsub -l /nodes=4/cpu=1 -I – # I want 2 cores on a node which has a Myrinet controler: oarsub -l /core=2 -p “myrinet='YES'” -I – # I want 5 nodes that are on the same switch: oarsub -l /switch=1/nodes=5 – # I want to connect to a node of the job number 1021: oarsub -C 1021

10. OAR usage When in non-interactive (batch) mode, the given program is launched on the first allocated node. Allocated resources hostnames are listed into the file whose name is contained into the $OAR_NODEFILE environment variable

11. The cpuset feature With the cpuset feature, you must use “oarsh” as a connector between nodes if you want a very good cleaning after the job is finished. You can enforce the usage of oarsh by simple sshd configuration. The cpuset feature may only be used on Linux kernels which have loaded the “cpuset” module

12. Visualisation tools MonikaDrawGantt

13. OAR coupled with PBS for CIGRI use