Partitions and Limits#
In SLURM multiple nodes can be grouped into partitions which are sets of nodes with associated limits for wall-clock time, job size, etc. These limits are hard limits for the jobs and can just be overruled by QOS (quality of service). The defined partitions can overlap, i.e. one node might be contained in several partitions.
Jobs are allocations of resources by users in order to execute tasks on the cluster for a specified period of time. Furthermore, the concept of job steps is used by SLURM to describe a set of different tasks within the job. One can imagine job steps as smaller allocations or jobs within the job, which can be executed sequentially or in parallel during the main job allocation.
The SLURM sinfo command lists all partitions and nodes managed by SLURM
on Levante as well as provides general information about the current nodes’ status:
$ sinfo
PARTITION AVAIL TIMELIMIT NODES STATE NODELIST
compute up 8:00:00 2200 alloc l[10000-10032,...,40322-40341]
compute up 8:00:00 32 idle l[40167-40174,40178-40183,40190-40195,40348-40359]
shared up 7-00:00:00 4 alloc l[10060,10063,10066,10069]
gpu down 12:00:00 4 idle l[40360,40363,40366,40369]
visualize down 12:00:00 4 drain lg[0-3]
interactive down 12:00:00 1 resv l10169
interactive down 12:00:00 3 alloc l[10160,10163,10166]
For detailed information about all available partitions and their limits
use the SLURM scontrol command as follows:
$ scontrol show partition
The following partitions are currently defined on Levante:
compute#
This partition consists of 2800 AMD EPYC 7763 Milan compute nodes and is intended for running parallel scientific applications. The compute nodes allocated for a job are used exclusively and cannot be shared with other jobs.
The partition contains nodes with different memory
configurations. If you want to use the
entire memory of a larger node, you have to request all memory with
the --mem=0 option.
interactive#
The interactive partition is made up of 15 nodes but can be dynamically expanded
if there is a short-term need. It is intended for memory or compute intensive
data processing and compilation tasks that should not run on the login nodes. Nodes
of this partition can be shared with other jobs if a single job does not allocate
all resources. Use salloc to allocate the resources and directly jump to that node.
Basically, this partition should not have any waiting times. The total amount of ressources
per user in this partition is limited to an equivalent of 2 nodes.
gpu#
The 60 nodes in this partition are each equipped with 2 AMD EPYC Milan 7713 CPUs and additional 4 Nvidia A100 GPUs. These can be used for GPGPU-aware scientific applications (e.g. via OpenACC programming) or interactive 3-dimensional data visualization via VirtualGL/TurboVNC.
visualize#
There are 4 dedicated nodes for interactive 3-dimensional data visualization. Access is granted only on request.
Warning
The following limits might be changed in the first months of levante general availability.
The SLURM limits configured for different partitions are:
Partition Name |
Max Nodes per Job |
Max Job Runtime |
Max resources used simultaneously |
Shared Node Usage |
Default Memory per CPU |
Max Memory per CPU |
|---|---|---|---|---|---|---|
compute |
512 |
8 hours |
no limit |
no |
960 MB |
3840 MB |
shared |
1 |
7 days |
512 CPUs |
yes |
960 MB |
960 MB |
interactive |
1 |
12 hours |
256 CPUs |
yes |
960 MB |
1920 MB |
gpu |
60 |
12 hours |
no limit |
yes |
960 MB |
3840 MB |
Hint
If your jobs require either longer execution times or more nodes, contact DKRZ Help Desk. The predefined limits can be adjusted for a limited time to match your purposes by specifying an appropriate Quality of Service (QOS). Please, include the following information in your request: the reason why you need higher limits, what limits to increase, and for how long those should be increased. Also a brief justification by your project admin is needed.
CAUTION: All jobs on levante have to be assigned to a partition - there is no default partition available. Choosing the partition can be done in various ways
Environment variable
export SBATCH_PARTITION=<partitionname>
Batch script option
#SBATCH [-p|--partition=]<partitionname>
Command line option
sbatch [-p|--partition=]<partitionname>
Note that an environment variable will override any matching option set in a batch script, and command line option will override any matching environment variable.
To control the job workload on the levante cluster and keep SLURM responsive, we enforce the following restrictions regarding the number of jobs:
SLURM Limits |
Max Number of Submitted Jobs |
Max Number of Running Jobs |
|---|---|---|
Per User and Account |
1000 |
20 |
If needed, you can ask for higher limits by sending a request with a short justification to support@dkrz.de. Based on the technical limitations and a fair share between all users, we might then arrange a QOS for some limited time.
To list job limits and quality of services relevant to you, use the sacctmgr command,
for example:
sacctmgr -s show user $USER
sacctmgr -s show user $USER format=user,account,maxjobs,maxsubmit,qos