---
title: Introduction
#tags:
keywords: introduction, home, welcome, architecture, design
last_updated: 07 September 2022
sidebar: merlin7_sidebar
permalink: /merlin7/introduction.html
redirect_from:
  - /merlin7
  - /merlin7/index.html
---

## About Merlin7

The Merlin7 cluster is moving toward **production** state since August 2024, this is expected latest by Q4 2025. Since January 2025 the system has been generally available,
but due to some remaining issues with the platform, the schedule of the migration of users and communities has been delayed. You will be notified well in advance
regarding the migration of data.

All PSI users can request access to Merlin7, please go to the [Requesting Merlin Accounts](/merlin7/request-account.html) page and complete the steps given there.

In case you identify errors or missing information, please provide feedback through [merlin-admins mailing list](mailto:merlin-admins@lists.psi.ch) mailing list or [submit a ticket using the PSI service portal](https://psi.service-now.com/psisp).

## Infrastructure

### Hardware

The Merlin7 cluster contains the following node specification:

| Node     | #N | CPU                                             | RAM             | GPU         | #GPUs |
| ----:    | -- | ---                                             | ---             | ----:       | ---:  |
| Login    |  2 | 2 AMD EPYC 7742 (64 Cores 2.25GHz)              | 512GB           |             |       |
| CPU      | 77 | 2 AMD EPYC 7742 (64 Cores 2.25GHz)              | 512GB           |             |       |
| GPU A100 |  8 | 2 AMD EPYC 7713 (64 Cores 3.2GHz)               | 512GB           | A100 80GB   |     4 |
| GPU GH   |  5 | NVIDIA ARM Grace Neoverse v2 (144 Cores 3.1GHz) | 864GB (Unified) | GH200 120GB |     4 |

### Network

The Merlin7 cluster builds on top of HPE/Cray technologies, including a high-performance network fabric called Slingshot. This network fabric is able
to provide up to 200 Gbit/s throughput between nodes. Further information on Slignshot can be found on at [HPE](https://www.hpe.com/psnow/doc/PSN1012904596HREN) and
at <https://www.glennklockwood.com/garden/slingshot>.

Through software interfaces like [libFabric](https://ofiwg.github.io/libfabric/) (which available on Merlin7), application can leverage the network seamlessly.

### Storage

Unlike previous iteration of the Merlin HPC clusters, Merlin7 _does not_ have any local storage. Instead storage for the entire cluster is provided through
a dedicated storage appliance from HPE/Cray called [ClusterStor](https://www.hpe.com/psnow/doc/PSN1012842049INEN.pdf).

The appliance is built of several storage servers:

* 2 management nodes
* 2 MDS servers, 12 drives per server, 2.9TiB (Raid10)
* 8 OSS-D servers, 106 drives per server, 14.5 T.B HDDs (Gridraid / Raid6)
* 4 OSS-F servers, 12 drives per server 7TiB SSDs (Raid10)

With effective storage capacity of:

* 10 PB HDD
  * value visible on linux: HDD 9302.4 TiB
* 162 TB SSD
  * value visible on linux: SSD 151.6 TiB
* 23.6 TiB on Metadata

The storage is directly connected to the cluster (and each individual node) through the Slingshot NIC.
