This document is for a development version of Ceph.

MDS Service

Deploy CephFS

One or more MDS daemons is required to use the CephFS file system. These are created automatically if the newer ceph fs volume interface is used to create a new file system. For more information, see FS volumes and subvolumes.

For example:

ceph fs volume create <fs_name> --placement="<placement spec>"

where fs_name is the name of the CephFS and placement is a Daemon Placement. For example, to place MDS daemons for the new foo volume on hosts labeled with mds:

ceph fs volume create foo --placement="label:mds"

You can also update the placement after-the-fact via:

ceph orch apply mds foo 'mds-[012]'

For manually deploying MDS daemons, use this specification:

service_type: mds
service_id: fs_name
  count: 3
  label: mds

The specification can then be applied using:

ceph orch apply -i mds.yaml

See Stateless services (MDS/RGW/NFS/rbd-mirror/iSCSI) for manually deploying MDS daemons on the CLI.

Further Reading

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