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1 | .. _cephfs-multifs: |
2 | ||
3 | Multiple Ceph File Systems | |
4 | ========================== | |
5 | ||
6 | ||
7 | Beginning with the Pacific release, multiple file system support is stable | |
8 | and ready to use. This functionality allows configuring separate file systems | |
9 | with full data separation on separate pools. | |
10 | ||
11 | Existing clusters must set a flag to enable multiple file systems:: | |
12 | ||
13 | ceph fs flag set enable_multiple true | |
14 | ||
15 | New Ceph clusters automatically set this. | |
16 | ||
17 | ||
18 | Creating a new Ceph File System | |
19 | ------------------------------- | |
20 | ||
21 | The new ``volumes`` plugin interface (see: :doc:`/cephfs/fs-volumes`) automates | |
22 | most of the work of configuring a new file system. The "volume" concept is | |
23 | simply a new file system. This can be done via:: | |
24 | ||
25 | ceph fs volume create <fs_name> | |
26 | ||
27 | Ceph will create the new pools and automate the deployment of new MDS to | |
28 | support the new file system. The deployment technology used, e.g. cephadm, will | |
29 | also configure the MDS affinity (see: :ref:`mds-join-fs`) of new MDS daemons to | |
30 | operate the new file system. | |
31 | ||
32 | ||
33 | Securing access | |
34 | --------------- | |
35 | ||
36 | The ``fs authorize`` command allows configuring the client's access to a | |
37 | particular file system. See also in :ref:`fs-authorize-multifs`. The client will | |
38 | only have visibility of authorized file systems and the Monitors/MDS will | |
39 | reject access to clients without authorization. | |
40 | ||
41 | ||
42 | Other Notes | |
43 | ----------- | |
44 | ||
45 | Multiple file systems do not share pools. This is particularly important for | |
46 | snapshots but also because no measures are in place to prevent duplicate | |
47 | inodes. The Ceph commands prevent this dangerous configuration. | |
48 | ||
49 | Each file system has its own set of MDS ranks. Consequently, each new file | |
50 | system requires more MDS daemons to operate and increases operational costs. | |
51 | This can be useful for increasing metadata throughput by application or user | |
52 | base but also adds cost to the creation of a file system. Generally, a single | |
53 | file system with subtree pinning is a better choice for isolating load between | |
54 | applications. |