=================================
 ceph-mon -- ceph monitor daemon
=================================

.. program:: ceph-mon

Synopsis
========

| **ceph-mon** -i *monid* [ --mon-data *mondatapath* ]


Description
===========

**ceph-mon** is the cluster monitor daemon for the Ceph distributed
file system. One or more instances of **ceph-mon** form a Paxos
part-time parliament cluster that provides extremely reliable and
durable storage of cluster membership, configuration, and state.

The *mondatapath* refers to a directory on a local file system storing
monitor data. It is normally specified via the ``mon data`` option in
the configuration file.

Options
=======

.. option:: -f, --foreground

   Foreground: do not daemonize after startup (run in foreground). Do
   not generate a pid file. Useful when run via :doc:`ceph-run <ceph-run>`\(8).

.. option:: -d

   Debug mode: like ``-f``, but also send all log output to stderr.

.. option:: -c ceph.conf, --conf=ceph.conf

   Use *ceph.conf* configuration file instead of the default
   ``/etc/ceph/ceph.conf`` to determine monitor addresses during
   startup.

.. option:: --mkfs

   Initialize the ``mon data`` directory with seed information to form
   and initial ceph file system or to join an existing monitor
   cluster.  Three pieces of information must be provided:

   - The cluster fsid.  This can come from a monmap (``--monmap <path>``) or
     explicitly via ``--fsid <uuid>``.
   - A list of monitors and their addresses.  This list of monitors
     can come from a monmap (``--monmap <path>``), the ``mon host``
     configuration value (in *ceph.conf* or via ``-m
     host1,host2,...``), or ``mon addr`` lines in *ceph.conf*.  If this
     monitor is to be part of the initial monitor quorum for a new
     Ceph cluster, then it must be included in the initial list,
     matching either the name or address of a monitor in the list.
     When matching by address, either the ``public addr`` or ``public
     subnet`` options may be used.
   - The monitor secret key ``mon.``.  This must be included in the
     keyring provided via ``--keyring <path>``.

.. option:: --keyring

   Specify a keyring for use with ``--mkfs``.


Availability
============

**ceph-mon** is part of the Ceph distributed file system. Please refer
to the Ceph documentation at http://ceph.com/docs for more
information.


See also
========

:doc:`ceph <ceph>`\(8),
:doc:`ceph-mds <ceph-mds>`\(8),
:doc:`ceph-osd <ceph-osd>`\(8)