diff --git a/sysadm/data-silos/cassandra/index.rst b/sysadm/data-silos/cassandra/index.rst
--- a/sysadm/data-silos/cassandra/index.rst
+++ b/sysadm/data-silos/cassandra/index.rst
@@ -5,3 +5,6 @@
 
 .. todo::
    This page is a work in progress.
+
+.. toctree::
+   installation
diff --git a/sysadm/data-silos/cassandra/installation.rst b/sysadm/data-silos/cassandra/installation.rst
new file mode 100644
--- /dev/null
+++ b/sysadm/data-silos/cassandra/installation.rst
@@ -0,0 +1,68 @@
+.. _cassandra_installation:
+
+How to install a cassandra node
+===============================
+
+.. admonition:: Intended audience
+   :class: important
+
+   sysadm staff members
+
+
+This page document the actions to configure a cassandra node and the associated instances
+
+.. - Prepare the puppet configuration
+
+Puppet configuration
+--------------------
+
+Implicit configuration
+^^^^^^^^^^^^^^^^^^^^^^
+
+By default, each cassandra instance is isolated in its own repositories:
+
+- `/etc/cassandra/<instance>`: the instance configuration
+- `cassandra@<instance>`: the systemd service (configured with a template and a drop-in
+  directory `/etc/systemd/system/cassandra@<instance>.d`)
+- `/var/log/cassandra/<instance>`: the log directory (the logs are also sent to the journal)
+- `/srv/cassandra/<instance>/commitlog`: the commitlog directory. It should be configured on a
+  different zfs pool than the data directory
+- `/srv/cassandra/<instance>/data`: the base data dir. The data, hints, system tables are stored
+  in this directory.
+
+Declare the node
+^^^^^^^^^^^^^^^^
+
+In the `common/cassandra.yaml` file, declare the node configuration:
+
+- Declare the node fqdn in the `cassandra::nodes` hash
+- List all the instances that need to be installed on the node and their eventual overrides
+- If the node is for a new cluster, also declare the cluster in the `cassandra::clusters` property
+
+System installation
+-------------------
+
+- Install the node with a debian bullseye distribution
+- Install zfs and configure the pools according to the instances that will run on the node.
+  Based on the usual cassandra server swh uses:
+
+  - one pool for the commitlogs using a fast write intensive disk
+  - one or several pools with the mixeduse disks
+
+- If the server name starts with `cassandra[0-9]+`, puppet will install all the necessary
+  packages and the configured instances.
+
+.. warning:: The services are just enabled, aka puppet doesn't force the service start. It's done
+  on purpose to let the system administrator control the restarts of the instances
+
+- Check the configuration looks correct and start the instance(s) with `systemctl start cassandra@<instance>`
+
+Monitoring
+^^^^^^^^^^
+
+TODO
+
+Metric
+^^^^^^
+
+TODO