Add basic GH200 hardware description

docs/alps/hardware.md

@@ -38,22 +38,44 @@ This approach to cooling provides greater efficiency for the rack-level cooling,
 
 Alps was installed in phases, starting with the installation of 1024 AMD Rome dual socket CPU nodes in 2020, through to the main installation of 2,688 Grace-Hopper nodes in 2024.
 
-There are currently four node types in Alps, with another becoming available in 2025:
+There are currently five node types in Alps:
 
-| type           | blades | nodes | CPU sockets | GPU devices |
-| ----           | ------:| -----:| -----------:| -----------:|
-| NVIDIA GH200   | 1344   | 2688  | 10,752      | 10,752      |
-| AMD Rome       |  256   | 1024  |  2,048      | --          |
-| NVIDIA A100    |   72   |  144  |    144      | 576         |
-| AMD MI250x     |   12   |   24  |     24      |  96         |
-| AMD MI300A     |   64   |  128  |    512      | 512         |
+| type           | abbreviation  | blades | nodes | CPU sockets | GPU devices |
+| ----           | -------       | ------:| -----:| -----------:| -----------:|
+| NVIDIA GH200   | gh200         | 1344   | 2688  | 10,752      | 10,752      |
+| AMD Rome       | zen2          |  256   | 1024  |  2,048      | --          |
+| NVIDIA A100    | a100          |   72   |  144  |    144      | 576         |
+| AMD MI250x     | mi200         |   12   |   24  |     24      |  96         |
+| AMD MI300A     | mi300         |   64   |  128  |    512      | 512         |
 
 [](){#ref-alps-gh200-node}
 ### NVIDIA GH200 GPU Nodes
 
-!!! todo
+!!! under-construction
+    The description of the GH200 nodes is a work in progress.
+    We will add more detailed information soon.
+    Please [get in touch](https://github.com/eth-cscs/cscs-docs/issues) if there is information that you want to see here.
+
+There are 24 cabinets, in 4 rows with 6 cabinets per row, and each cabinet contains 112 nodes (for a total of 448 GH200):
+* 8 chassis per cabinet
+* 7 blades per chassis
+* 2 nodes per blade
+
+!!! info "Why 7 blades per chassis?"
+    A chassis can contain up to 8 blades, however Alps' gh200 chassis are underpopulated so that we can increase the amount of power delivered to each GPU.
 
-Blanca Peak
+Each node contains four Grace-Hopper modules and four corresponding network interface cards (NICS) per blade, as illustrated below:
+
+![](../images/alps/gh200-schematic.svg)
+
+??? info "Node xname"
+    There are two boards per blade with one node per board.
+    This is different to the `zen2` CPU-only nodes (used for example in Eiger) that have two nodes per board for a total of four nodes per blade.
+    As such, there are no `n1` nodes in the xname list, e.g.:
+    ```
+    x1100c0s6b0n0
+    x1100c0s6b1n0
+    ```
 
 [](){#ref-alps-zen2-node}
 ### AMD Rome CPU Nodes
@@ -79,6 +101,8 @@ Bard Peak
 [](){#ref-alps-mi300-node}
 ### AMD MI300A GPU Nodes
 
+![](../images/alps/mi300-schematic.svg)
+
 !!! todo
 
 Parry Peak

docs/contributing/index.md

@@ -229,6 +229,66 @@ They stand out better from the main text, and can be collapsed by default if nee
 
 If an admonition is collapsed by default, it should have a title.
 
+We provide some custom admonitions.
+
+#### Change
+
+For adding information about a change, originally designed for recording updates to clusters.
+
+=== "Rendered"
+    !!! change "2025-04-17"
+        * SLURM was upgraded to version 25.1.
+        * uenv was upgraded to v0.8
+
+    Old changes can be folded:
+
+    ??? change "2025-02-04"
+        * The new Scratch cleanup policy was implemented
+        * NVIDIA driver was updated
+
+=== "Markdown"
+    ```
+    !!! change "2025-04-17"
+        * SLURM was upgraded to version 25.1.
+        * uenv was upgraded to v0.8
+    ```
+
+    Old changes can be folded:
+
+    ```
+    ??? change "2025-02-04"
+        * The new Scratch cleanup policy was implemented
+        * NVIDIA driver was updated
+    ```
+
+#### Under construction
+
+For marking incomplete sections.
+
+=== "Rendered"
+    !!! under-construction
+        This is not finished yet!
+
+=== "Markdown"
+    ```
+    !!! under-construction
+        This is not finished yet!
+    ```
+
+#### Todo
+
+As a placeholder for documentation that needs to be written.
+
+=== "Rendered"
+    !!! todo
+        Add some common error messages and how to fix them.
+
+=== "Markdown"
+    ```
+    !!! todo
+        Add some common error messages and how to fix them.
+    ```
+
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