---
title: Accessing Slurm Cluster
#tags:
#keywords:
last_updated: 13 June 2019
#summary: ""
sidebar: merlin6_sidebar
permalink: /merlin6/slurm-access.html
---

## The Merlin6 Slurm batch system

Clusters at PSI use the [Slurm Workload Manager](http://slurm.schedmd.com/) 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.
* Two different Slurm clusters exist: **merlin5** and **merlin6**.
   * **merlin5** is a cluster with very old hardware (out-of-warranty).
   * **merlin5** will exist as long as hardware incidents are soft and easy to repair/fix (i.e. hard disk replacement)
   * **merlin6** is the default cluster when submitting jobs.

Please follow the section **Merlin6 Slurm** for more details about configuration and job submission.

### Merlin5 Access

Keeping the **merlin5** cluster will allow 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.
However, users can keep submitting to the old **merlin5** computing nodes by using the option ``--cluster=merlin5`` and using the corresponding
Slurm partition with ``--partition=merlin``. In example:

```bash
srun --clusters=merlin5 --partition=merlin hostname
sbatch --clusters=merlin5 --partition=merlin myScript.batch
```

### Merlin6 Access

By default, any job submitted with specifying ``--clusters=`` should use the local cluster, so nothing extra should be specified. In any case,
you can optionally add ``--clusters=merlin6`` in order to force submission to the Merlin6 cluster.