sysadm: add a postgresql backup management section

sysadm/data-silos/postgresql/backup.rst

+.. _postgresql_backups:
+
+How to manage the PostgreSQL backups
+====================================
+
+.. admonition:: Intended audience
+   :class: important
+
+   sysadm staff members
+
+The archive's postgresql is backed up every week by barman.
+
+The service is running on ``banco``
+
+List the servers with backups
+-----------------------------
+
+.. code:: bash
+
+    root@banco:~# sudo -u barman barman list-server
+    swh-10 - Software Heritage Database (inactive)
+    swh-11 - Software Heritage Database (inactive)
+    swh-12 - Software Heritage Database
+
+List the backups of a server
+----------------------------
+
+.. code:: bash
+
+    root@banco:~# sudo -u barman barman list-backup swh-12
+    swh-12 20220207T153405 - STARTED
+    swh-12 20220129T003102 - Mon Jan 31 11:09:42 2022 - Size: 17.3 TiB - WAL Size: 425.5 GiB
+    swh-12 20220122T003103 - Mon Jan 24 19:41:52 2022 - Size: 17.0 TiB - WAL Size: 608.4 GiB
+
+Manually delete a backup
+------------------------
+
+.. code:: bash
+
+    root@banco:~# sudo -u barman barman delete swh-12 20220115T003103
+    Deleting backup 20220115T003103 for server swh-12
+    Delete associated WAL segments:
+        00000001000266820000004E
+        00000001000266820000004F
+        000000010002668200000050
+    ...
+    Deleted backup 20220115T003103 (start time: Mon Feb  7 15:24:00 2022, elapsed time: 6 minutes, 56 seconds)
+
+Manually start a backup
+-----------------------
+
+A backup can take several days to complete, so don't forget to launch it in a tmux or equivalent.
+
+.. code:: bash
+
+    root@banco:~# sudo -u barman barman backup swh-12
+    Starting backup using rsync-concurrent method for server swh-12 in /srv/barman/swh-12/base/20220207T153405
+    Backup start at LSN: 26F60/E5916DD0 (0000000100026F60000000E5, 00916DD0)
+    Starting backup copy via rsync/SSH for 20220207T153405
+    ...
+
+Check the progress:
+
+.. code:: bash
+
+    root@banco:~# sudo -u barman barman list-backup swh-12
+    swh-12 20220207T153405 - STARTED
+    swh-12 20220129T003102 - Mon Jan 31 11:09:42 2022 - Size: 17.3 TiB - WAL Size: 426.1 GiB
+    swh-12 20220122T003103 - Mon Jan 24 19:41:52 2022 - Size: 17.0 TiB - WAL Size: 608.4 GiB
+

sysadm/data-silos/postgresql/index.rst

@@ -5,3 +5,4 @@ PostgreSQL
 
 .. toctree::
    howto-connect
+   backup