Partitions

To manage the large amount of nodes on CARL and EDDY, its important to work with partitions. Partitions will optimize the way resources are given out to users and to ensure that everyone can submit jobs and receive results as fast as possible.

Since we are using SLURM as our cluster manager and job scheduling system, informations about partions can be displayed by using the command:

sinfo

The command "sinfo" has many possible options. Some important ones are:

• -a, --all

Display information about all partitions. You will even see partitions that are not available for your group and hidden partitions.

• -l, --long

Display more detailed informations about the available partitions.

• -N, --Node

Display a list of every available node.

• -n <nodes>, --nodes=<nodes>

Display informations about a specific node. Multiple nodes may be comma separated. You can even specify a range of nodes, e.g. mpcs[100-120].

• -O <output_format>, --Format=<output_format>

Specify the information you want to be displayed.

If you want to, for example, display the node hostname, the number of CPUs, the CPU load, the amount of free memory, the size of temporary disk, the size of memory per node (in megabytes) you could use the following command:

sinfo -O nodehost,cpus,cpusload,freemem,disk,memoryHOSTNAMES           CPUS                CPU_LOAD            FREE_MEM            TMP_DISK            MEMORY

cfdh076 24 1.01 97568 115658 128509

The size of each field can be modified (syntax: "type[:[.]size]") to match your needs, for example like this:

sinfo -O nodehost:8,cpus:5,cpusload:8,freemem:10,disk:10,memory:8

Output:

HOSTNAMECPUS CPU_LOADFREE_MEM  TMP_DISK  MEMORY
cfdh076 24   1.01    97568     115658    128509

The full list and further informations about the command "sinfo" can be found here: sinfo

Partitions on CARL/EDDY

Using sinfo on CARL/EDDY will display an output like this:

Informations you can see in the screenshot described by columns:

1. PARTITIONS

   Name of a partition, e.g. all_nodes.p

2. AVAIL

   State of the partitions (up or down)

3. TIMELIMIT

   Maximum time limit for any user job in days-hours:minutes:seconds.

4. NODES

   Count of nodes with this particular configuration.

5. STATE

   Current state of the node. Possible states are: allocated, completing, down, drained, draining, fail, failing, future, idle, maint, mixed, perfctrs, power_down, power_up, reserved, and unknown

6. NODELIST

   Names of nodes associated with this configuration/partition.

The full description of the output field can be found here: output field

Usage of the Partitions on CARL/EDDY

To optimize the submission, the runtime and the overall usage for everybody using the cluster, you should always specify the right partition for your jobs. For the following examples, a distinction is drawn between short, mediocre and long jobs: