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| layout | title | parent | grand_parent | nav_order |
|---|---|---|---|---|
| default | Slurm Configuration | Merlin6 Slurm | Merlin6 User Guide | 2 |
Slurm Configuration
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Table of contents
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Using the Slurm batch system
Clusters at PSI use the Slurm Workload Manager as the batch system technology for managing and scheduling jobs. Historically, Merlin4 and Merlin5 also used Slurm. In the same way, Merlin6 has been also configured with this batch system.
Slurm has been installed in a multi-clustered configuration, allowing to integrate multiple clusters in the same batch system.
For understanding the Slurm configuration setup in the cluster, sometimes may be useful to check the following files:
/etc/slurm/slurm.conf- can be found in the login nodes and computing nodes./etc/slurm/cgroup.conf- can be found in the computing nodes, is also propagated to login nodes for user read access./etc/slurm/gres.conf- can be found in the GPU nodes, is also propgated to login nodes and computing nodes for user read access.
The previous configuration files which can be found in the login nodes, correspond exclusively to the merlin6 cluster configuration files. Configuration files for the old merlin5 cluster must be checked directly on any of the merlin5 computing nodes: these are not propagated to the merlin6 login nodes.
About Merlin5 & Merlin6
The new Slurm cluster is called merlin6. However, the old Slurm merlin cluster will be kept for some time, and it has been renamed to merlin5. It will allow to keep running jobs in the old computing nodes until users have fully migrated their codes to the new cluster.
From July 2019, merlin6 becomes the default cluster and any job submitted to Slurm will be submitted to that cluster. Users can keep submitting to
the old merlin5 computing nodes by using the option --cluster=merlin5.
In this documentation is only explained the usage of the merlin6 Slurm cluster.
Using Slurm 'merlin6' cluster
Basic usage for the merlin6 cluster will be detailed here. For advanced usage, please use the following document LINK TO SLURM ADVANCED CONFIG
Merlin6 Node definition
The following table show default and maximum resources that can be used per node:
| Nodes | Def.#CPUs | Max.#CPUs | Def.Mem/CPU | Max.Mem/CPU | Max.Mem/Node | Max.Swap | Def.#GPUs | Max.#GPUs |
|---|---|---|---|---|---|---|---|---|
| merlin-c-[001-022,101-122,201-222] | 1 core | 44 cores | 8000 | 352000 | 352000 | 10000 | N/A | N/A |
| merlin-g-[001] | 1 core | 8 cores | 8000 | 102498 | 102498 | 10000 | 1 | 2 |
| merlin-g-[002-009] | 1 core | 10 cores | 8000 | 102498 | 102498 | 10000 | 1 | 4 |
If nothing is specified, by default each core will use up to 8GB of memory. More memory per core can be specified with the --mem=<memory> option,
and maximum memory allowed is Max.Mem/Node.
In Merlin6, memory is considered a Consumable Resource, as well as the CPU.
Merlin6 Slurm partitions
Partition can be specified when submitting a job with the --partition=<partitionname> option.
The following partitions (also known as queues) are configured in Slurm:
| Partition | Default Partition | Default Time | Max Time | Max Nodes | Priority |
|---|---|---|---|---|---|
| general | true | 1 day | 1 week | 50 | low |
| daily | false | 1 day | 1 day | 60 | medium |
| hourly | false | 1 hour | 1 hour | unlimited | highest |
General is the default, so when nothing is specified job will be by default assigned to that partition. General can not have more than 50 nodes running jobs. For daily this limitation is extended to 60 nodes while for hourly there are no limits. Shorter jobs have more priority than longer jobs, hence in general terms would be scheduled before (however, other factors such like user fair share value can affect to this decision).
Merlin6 User limits
By default, users can not use more than 528 cores at the same time (Max CPU per user). This limit applies for the general and daily partitions. For the hourly partition, there is no restriction. These limits are softed for the daily partition during non working hours and during the weekend as follows:
| Partition | Mon-Fri 08h-18h | Sun-Thu 18h-0h | From Fri 18h to Sun 8h | From Sun 8h to Mon 18h |
|---|---|---|---|---|
| general | 528 | 528 | 528 | 528 |
| daily | 528 | 792 | Unlimited | 792 |
| hourly | Unlimited | Unlimited | Unlimited | Unlimited |