---
name: "ceph-mon"
section: "8"
platform: "linux"
package: "ceph-mon"
version: "18.2.7+ds-1+deb13u1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/ceph-mon"
---

# ceph-mon(8)

ceph monitor daemon

## NAME

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)](/ceph-run/8.md).

- **-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.

## SEE ALSO

[*ceph*(8)](/ceph/8.md), [*ceph-mds*(8)](/ceph-mds/8.md), [*ceph-osd*(8)](/ceph-osd/8.md)

## COPYRIGHT

2010-2014, Inktank Storage, Inc. and contributors. Licensed under Creative Commons Attribution Share Alike 3.0 (CC-BY-SA-3.0)