Ceph monitors are light-weight processes that maintain a master copy of the
cluster map. You can run a cluster with 1 monitor. We recommend at least 3
monitors for a production cluster. Ceph monitors use a variation of the
-`Paxos_` protocol to establish consensus about maps and other critical
+`Paxos`_ protocol to establish consensus about maps and other critical
information across the cluster. Due to the nature of Paxos, Ceph requires
a majority of monitors running to establish a quorum (thus establishing
consensus).
If you are adding a new host when adding a new monitor, see `Hardware
Recommendations`_ for details on minimum recommendations for monitor hardware.
To add a monitor host to your cluster, first make sure you have an up-to-date
-version of Linux installed (typically Ubuntu 12.04 precise).
+version of Linux installed (typically Ubuntu 14.04 or RHEL 7).
Add your monitor host to a rack in your cluster, connect it to the network
and ensure that it has network connectivity.
-----------------------------
For manually deployed clusters, you must install Ceph packages
-manually. See `Installing Debian/Ubuntu Packages`_ for details.
+manually. See `Installing Packages`_ for details.
You should configure SSH to a user with password-less authentication
and root permissions.
-.. _Installing Debian/Ubuntu Packages: ../../../install/debian
-
+.. _Installing Packages: ../../../install/install-storage-cluster
.. _Adding a Monitor (Manual):
without the ``mon.`` prefix (i.e., ``{mon-id}`` should be the ``a``
on ``mon.a``).
-#. Create the default directory on your new monitor. ::
+#. Create the default directory on the machine that will host your
+ new monitor. ::
ssh {new-mon-host}
sudo mkdir /var/lib/ceph/mon/ceph-{mon-id}
#. Create a temporary directory ``{tmp}`` to keep the files needed during
- this process. This directory should be different from monitor's default
+ this process. This directory should be different from the monitor's default
directory created in the previous step, and can be removed after all the
- steps are taken. ::
+ steps are executed. ::
mkdir {tmp}
#. Retrieve the keyring for your monitors, where ``{tmp}`` is the path to
- the retrieved keyring, and ``{filename}`` is the name of the file containing
- the retrieved monitor key. ::
+ the retrieved keyring, and ``{key-filename}`` is the name of the file
+ containing the retrieved monitor key. ::
- ceph auth get mon. -o {tmp}/{filename}
+ ceph auth get mon. -o {tmp}/{key-filename}
#. Retrieve the monitor map, where ``{tmp}`` is the path to
- the retrieved monitor map, and ``{filename}`` is the name of the file
+ the retrieved monitor map, and ``{map-filename}`` is the name of the file
containing the retrieved monitor monitor map. ::
- ceph mon getmap -o {tmp}/{filename}
+ ceph mon getmap -o {tmp}/{map-filename}
#. Prepare the monitor's data directory created in the first step. You must
specify the path to the monitor map so that you can retrieve the
information about a quorum of monitors and their ``fsid``. You must also
specify a path to the monitor keyring::
- sudo ceph-mon -i {mon-id} --mkfs --monmap {tmp}/{filename} --keyring {tmp}/{filename}
+ sudo ceph-mon -i {mon-id} --mkfs --monmap {tmp}/{map-filename} --keyring {tmp}/{key-filename}
#. Add the new monitor to the list of monitors for you cluster (runtime). This enables
to determine the current state of the system accurately. Consequently, making
changes to an existing monitor's IP address must be done with great care.
-.. _Paxos: http://en.wikipedia.org/wiki/Paxos_(computer_science)
-
Changing a Monitor's IP address (The Right Way)
-----------------------------------------------
.. _Manual Deployment: ../../../install/manual-deployment
.. _Monitor Bootstrap: ../../../dev/mon-bootstrap
+.. _Paxos: http://en.wikipedia.org/wiki/Paxos_(computer_science)
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