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 # `cinder`
+
+## Configuring backup storage
+
+Cinder supports a wide variety of storage backends to store volume backups. They
+can be referenced from the [Cinder documentation](https://docs.openstack.org/cinder/latest/configuration/block-storage/backup-drivers.html).
+
+### Ceph
+
+It is possible to backup volumes into a Ceph cluster.  You are able to store
+the backups inside the same Ceph cluster that is deployed by Atmosphere or an
+external cluster that you deploy.
+
+#### Atmosphere
+
+If you're looking to use the Ceph cluster that is deployed by Atmosphere, you
+will need to simply set the following inventory variables:
+
+```yaml
+cinder_helm_values:
+  conf:
+    cinder:
+      DEFAULT:
+        backup_driver: cinder.backup.drivers.ceph.CephBackupDriver
+```
+
+> **Warnings**
+>
+> It's not recommended to use same backend for volumes and backups. If you are
+> using Atmosphere's Ceph for volumes, you should use a different Ceph cluster
+> for backups.
+
+#### External
+
+If you want to use an external Ceph cluster, you will need to set the following
+inventory variables:
+
+```yaml
+cinder_helm_values:
+  conf:
+    cinder:
+      DEFAULT:
+        backup_driver: cinder.backup.drivers.ceph.CephBackupDriver
+        backup_ceph_user: cinder
+        backup_ceph_pool: backups
+  backup:
+    external_ceph_rbd:
+      enabled: true
+      admin_keyring: AQCBYNhjMtiXEBAA3weDsYA2zoPqOXTRijQtzg==
+      conf:
+        global:
+          fsid: 795115d3-2b3d-567f-b5f8-72703d896b56
+          mon host: 10.96.240.153,10.96.240.126,10.96.240.240
+```
+
+Atmosphere will automatically create a `cephx` user which matches the provided
+`backup_ceph_user` variable.  It will also create a pool with the name of the
+`backup_ceph_pool` variable.