ceph/doc/cephfs/add-remove-mds.rst
Jos Collin bf34da0ee7 doc: create add/remove metadata server
A new doc is created based on https://github.com/ceph/ceph/pull/22035#pullrequestreview-121600153.

Fixes: http://tracker.ceph.com/issues/24093
Signed-off-by: Jos Collin <jcollin@redhat.com>
2018-06-01 18:49:46 +05:30

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Add/Remove Metadata Server
============================
.. important:: You must deploy at least one metadata server to use CephFS.
There is experimental support for running multiple metadata servers.
Do not run multiple active metadata servers in production.
See `MDS Config Reference`_ for details on configuring metadata servers.
Add a Metadata Server
=====================
#. Create an mds data point ``/var/lib/ceph/mds/mds.<your-mds-id>``.
#. Edit ``ceph.conf`` and add MDS section. ::
[mds.<your-mds-id>]
host = {hostname}
#. Create the authentication key, if you use CephX. ::
$ sudo ceph auth get-or-create mds.<your-mds-id> mon 'profile mds' mgr 'profile mds' mds 'allow *' osd 'allow *' > /var/lib/ceph/mds/ceph-<your-mds-id>/keying
#. Start the service. ::
$ sudo service ceph start mds.<your-mds-id>
#. The status of the cluster shows: ::
mds: cephfs_a-1/1/1 up {0=c=up:active}, 3 up:standby
Remove a Metadata Server
========================
.. note:: Ensure that if you remove a metadata server, the remaining metadata
servers will be able to service requests from CephFS clients. If that is not
possible, consider adding a metadata server before destroying the metadata
server you would like to take offline.
If you have a metadata server in your cluster that you'd like to remove, you may use
the following method.
#. Create a new Metadata Server as shown in the above section.
#. Stop the old Metadata Server and start using the new one. ::
$ ceph mds fail <mds name>
#. Remove the ``/var/lib/ceph/mds/mds.<your-mds-id>`` directory on the old Metadata server.
.. _MDS Config Reference: ../mds-config-ref