#acl DvGroup:read,write,delete,revert,admin All:read 
=== Slurm Installation for Pax Cluster ===
Slurm is currently being tested as scheduler for the pax11 machines, named pax11-[00-31]. At the moment, interactive logins to these machines are possible, this will probably change in a production setup.

==== Kerberos Integration ====

<!> You need to acquire an addressless Kerberos ticket for Slurm to work. This is the default on supported DESY machines. On self-maintained machines like notebooks, simply set {{{noaddresses=true}}} in the file {{{/etc/krb5.conf}}}. To check if your ticket is addressless, call {{{klist -v}}} (Heimdal klist only).

Slurm was configured to always schedule complete nodes to each job.

<!> At the moment, ticket renewal does not work, this is a bug in the auks software.
==== Slurm Commands ====
The most important commands:
||[[http://slurm.schedmd.com/sinfo.html|sinfo]]||Information about the cluster||
||[[http://slurm.schedmd.com/squeue.html|squeue]]||Show current job list ||
||[[http://slurm.schedmd.com/srun.html|srun]]  ||Parallel command execution||
||[[http://slurm.schedmd.com/sbatch.html|sbatch]]||Submit a batch job||
||[[http://slurm.schedmd.com/scancel.html|scancel]]||Abort a job||
||[[http://slurm.schedmd.com/sacct.html|sacct]] ||Show accounting information||

===== Batch access =====
Job scripts submitted to Slurm using the sbatch command must be readable for the slurm daemon, so they cannot require an AFS token to access them. Better place the job script on Lustre.

===== Parallel Execution =====
Slurm has integrated execution support for parallel programs, there is no need to use mpirun or mpiexec. To start a program in a job script or interactive session, use a command like {{{srun -n 4 -N 2 hostname}}}. This will execute the command {{{hostname}}} 4 times on 2 different machines.
===== MPI Support =====
srun can execute MPI programs, but the LD_LIBRARY_PATH must first be set, this is done by loading the right environment module, e.g. {{{module add openmpi-x86_64}}}. For openmpi, the command line option --resv-ports is needed for srun.
==== Job scripts ====
Parameters to slurm can be set on the sbatch command line or starting with a {{{#SBATCH}}} in the script.
The most important parameters are:
||-J ||job name||
||--get-user-env||copy environment variables||
||-n ||number of cores||
||-N ||number of nodes||
||-t ||run time of the job, default is 30 minutes||
||-A ||account, default the same as UNIX group||
||-p ||partition of the cluster||
||--switches||maximum number of switches connecting the allocated nodes||
||--mail-type||configure email notifications, e.g. use --mail-type=ALL||

===== Time format =====
The runtime of a job is given as minutes, hours and minutes (HH:MM) or days and hours (DD-HH). The maximum run time was set to 48 hours.

===== Examples =====
An example job script is in [[attachment:slurm-mpi.job]]

==== Accounting ====
The jobs and their resources usage is stored in a database that is used for the fair share part of the scheduler. You can view your account's jobs with the command {{{sacct}}}. With no parameters,only today's jobs are shown, to view all jobs since May 1st, use the command {{{sacct -S 2014-05-01}}} . To view jobs from other accounts as well, use the {{{--allusers}}} option.