update sources to 12.2.7

[ceph.git] / ceph / doc / cephfs / administration.rst

diff --git a/ceph/doc/cephfs/administration.rst b/ceph/doc/cephfs/administration.rst
index 23bd5fc6a991ed222b42b1b7117166eba01b7be8..71a0e4075d10fb00c5db9255aa8cc22c8d1d6593 100644 (file)
--- a/ceph/doc/cephfs/administration.rst
+++ b/ceph/doc/cephfs/administration.rst
@@ -74,6 +74,22 @@ appear to be eg. exabytes in size, causing load on the MDS as it tries
 to enumerate the objects during operations like stats or deletes.
 
 
+Taking the cluster down
+-----------------------
+
+Taking a CephFS cluster down is done by reducing the number of ranks to 1,
+setting the cluster_down flag, and then failing the last rank. For example:
+
+::
+    ceph fs set <fs_name> max_mds 1
+    ceph mds deactivate <fs_name>:1 # rank 2 of 2
+    ceph status # wait for rank 1 to finish stopping
+    ceph fs set <fs_name> cluster_down true
+    ceph mds fail <fs_name>:0
+
+Setting the ``cluster_down`` flag prevents standbys from taking over the failed
+rank.
+
 Daemons
 -------
 
@@ -81,16 +97,36 @@ These commands act on specific mds daemons or ranks.
 
 ::
 
-    mds fail <gid/name/role
+    mds fail <gid/name/role>
+
+Mark an MDS daemon as failed.  This is equivalent to what the cluster
+would do if an MDS daemon had failed to send a message to the mon
+for ``mds_beacon_grace`` second.  If the daemon was active and a suitable
+standby is available, using ``mds fail`` will force a failover to the standby.
+
+If the MDS daemon was in reality still running, then using ``mds fail``
+will cause the daemon to restart.  If it was active and a standby was
+available, then the "failed" daemon will return as a standby.
 
-This command deactivates an MDS causing it to flush its entire journal to
+::
+
+    mds deactivate <role>
+
+Deactivate an MDS, causing it to flush its entire journal to
 backing RADOS objects and close all open client sessions. Deactivating an MDS
 is primarily intended for bringing down a rank after reducing the number of
-active MDS (max_mds).
+active MDS (max_mds). Once the rank is deactivated, the MDS daemon will rejoin the
+cluster as a standby.
+``<role>`` can take one of three forms:
 
 ::
 
-    mds deactivate <role>
+    <fs_name>:<rank>
+    <fs_id>:<rank>
+    <rank>
+
+Use ``mds deactivate`` in conjunction with adjustments to ``max_mds`` to
+shrink an MDS cluster.  See :doc:`/cephfs/multimds`
 
 ::