Create a Ceph filesystemΒΆ

Tip

The ceph fs new command was introduced in Ceph 0.84. Prior to this release, no manual steps are required to create a filesystem, and pools named data and metadata exist by default.

The Ceph command line now includes commands for creating and removing filesystems, but at present only one filesystem may exist at a time.

A Ceph filesystem requires at least two RADOS pools, one for data and one for metadata. When configuring these pools, you might consider:

  • Using a higher replication level for the metadata pool, as any data loss in this pool can render the whole filesystem inaccessible.
  • Using lower-latency storage such as SSDs for the metadata pool, as this will directly affect the observed latency of filesystem operations on clients.

Refer to Pools to learn more about managing pools. For example, to create two pools with default settings for use with a filesystem, you might run the following commands:

$ ceph osd pool create cephfs_data <pg_num>
$ ceph osd pool create cephfs_metadata <pg_num>

Once the pools are created, you may enable the filesystem using the fs new command:

$ ceph fs new <fs_name> <metadata> <data>

For example:

$ ceph fs new cephfs cephfs_metadata cephfs_data
$ ceph fs ls
name: cephfs, metadata pool: cephfs_metadata, data pools: [cephfs_data ]

Once a filesystem has been created, your MDS(s) will be able to enter an active state. For example, in a single MDS system:

$ ceph mds stat
e5: 1/1/1 up {0=a=up:active}

Once the filesystem is created and the MDS is active, you are ready to mount the filesystem. If you have created more than one filesystem, you will choose which to use when mounting.