---
title: Cluster 'merlin5'
#tags:
#keywords:
last_updated: 07 April 2021
#summary: "Merlin 5 cluster overview"
sidebar: merlin6_sidebar
permalink: /merlin5/cluster-introduction.html
---

## Slurm 'merlin5' cluster

**Merlin5** was the old official PSI Local HPC cluster for development and
mission-critical applications which was built in 2016-2017. It was an
extension of the Merlin4 cluster and built from existing hardware due 
to a lack of central investment on Local HPC Resources. **Merlin5** was 
then replaced by the **[Merlin6](/merlin6/index.html)** cluster in 2019,
with an important central investment of ~1,5M CHF. **Merlin5** was mostly 
based on CPU resources, but also contained a small amount of GPU-based 
resources which were mostly used by the BIO experiments.

**Merlin5** has been kept as a **Local HPC [Slurm](https://slurm.schedmd.com/overview.html) cluster**,
called **`merlin5`**. In that way, the old CPU computing nodes are still available as extra computation resources,
and as an extension of the official production **`merlin6`** [Slurm](https://slurm.schedmd.com/overview.html) cluster.

The old Merlin5 _**login nodes**_, _**GPU nodes**_ and _**storage**_ were fully migrated to the **[Merlin6](/merlin6/index.html)** 
cluster, which becomes the **main Local HPC Cluster**. Hence, **[Merlin6](/merlin6/index.html)**
contains the storage which is mounted on the different Merlin HPC [Slurm](https://slurm.schedmd.com/overview.html) Clusters (`merlin5`, `merlin6`, `gmerlin6`).

### Submitting jobs to 'merlin5'

To submit jobs to the **`merlin5`** Slurm cluster, it must be done from the **Merlin6** login nodes by using
the option `--clusters=merlin5` on any of the Slurm commands (`sbatch`, `salloc`, `srun`, etc. commands).

## The Merlin Architecture

### Multi Non-Federated Cluster Architecture Design: The Merlin cluster

The following image shows the Slurm architecture design for Merlin cluster.
It contains a multi non-federated cluster setup, with a central Slurm database
and multiple independent clusters (`merlin5`, `merlin6`, `gmerlin6`):

![Merlin6 Slurm Architecture Design]({{ "/images/merlin-slurm-architecture.png" }})