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docs/merlin6/introduction.md

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+# Introduction
+
+!!! note
+    Merlin6 is no longer accessible for new users! Please have a look at [Merlin 7](../../merlin7/01-Quick-Start-Guide/introduction.md) instead.
+
+## Slurm clusters
+
+Comprised the **`merlin6`** CPU cluster and the
+[**`gmerlin6`**](../gmerlin6/cluster-introduction.md) GPU cluster. A legacy
+cluster (formally called [**`merlin5`**](../merlin5/cluster-introduction.md) is
+kept active with best effort support.
+
+From July 2019, **`merlin6`** becomes the **default Slurm cluster** and any job submitted from the login node will be submitted to that cluster if not.
+
+* Users can keep submitting to the old *`merlin5`* computing nodes by using the option ``--cluster=merlin5``.
+* Users submitting to the **`gmerlin6`** GPU cluster need to specify the option ``--cluster=gmerlin6``.
+
+### Slurm 'merlin6'
+
+**CPU nodes** are configured in a **Slurm** cluster, called **`merlin6`**, and
+this is the ***default Slurm cluster***. Hence, by default, if no Slurm cluster is
+specified (with the `--cluster` option), this will be the cluster to which the jobs
+will be sent.