Add local ssd on nova compute nodes (#249)

Signed-off-by: Christian Berendt <berendt@osism.tech>

docs/guides/configuration-guide/openstack/nova.md

@@ -50,3 +50,33 @@ reserved_host_memory_mb = 32768
 [DEFAULT]
 reserved_host_cpus = 4
 ```
+
+## Local SSD storage
+
+In this example, a local SSD is provided for use on compute node `testbed-node-0`.
+
+On the compute node, the local SSD to be used is formatted with a file system of
+your choice and mounted to `/var/lib/nova`. When using more than one local SSD, a
+software RAID 1 should be used
+
+A `nova.conf` is created as an overlay for the compute node `testbed-node-0`.
+
+```ini title="environments/kolla/files/overlays/testbed-node-0/nova.conf"
+[libvirt]
+images_type = raw
+
+[glance]
+enable_rbd_download = true
+```
+
+In the inventory, the parameters `nova_instance_datadir_volume` and `nova_backend_ceph`
+are added in the section for the `kolla` environment.
+
+
+```yaml title="inventory/host_vars/testbed-node-0.yml"
+##########################################################
+# kolla
+
+nova_instance_datadir_volume: /var/lib/nova
+nova_backend_ceph: no
+```