Notice

This document is for a development version of Ceph.

# ceph-mon – ceph monitor daemon¶

## 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¶

-f, --foreground

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

-d

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

--setuser userorgid

Set uid after starting. If a username is specified, the user record is looked up to get a uid and a gid, and the gid is also set as well, unless –setgroup is also specified.

--setgroup grouporgid

Set gid after starting. If a group name is specified the group record is looked up to get a gid.

-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.

--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 (for backward compatibility) the deprecated 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>.

--keyring

Specify a keyring for use with --mkfs.

--no-config-file

Signal that we don’t want to rely on a ceph.conf, either user provided or the default, to run the daemon. This will entail providing all necessary options to the daemon as arguments.

## Availability¶

ceph-mon is part of Ceph, a massively scalable, open-source, distributed storage system. Please refer to the Ceph documentation at https://docs.ceph.com for more information.