``osd_scrub_end_week_day`` are 0 - 6. The use of 7 is now illegal.
Specifying ``0`` for both values causes every day of the week to be allowed.
+* Multiple file systems in a single Ceph cluster is now stable. New Ceph clusters
+ enable support for multiple file systems by default. Existing clusters
+ must still set the "enable_multiple" flag on the fs. Please see the CephFS
+ documentation for more information.
+
* A new health check, DAEMON_OLD_VERSION, will warn if different versions of Ceph are running
on daemons. It will generate a health error if multiple versions are detected.
This condition must exist for over mon_warn_older_version_delay (set to 1 week by default) in order for the
fragmentation) but stub out the balancing policies using Lua. For details, see
:doc:`/cephfs/mantle`.
-Snapshots
----------
-Like multiple active MDSes, CephFS is designed from the ground up to support
-snapshotting of arbitrary directories. There are no known bugs at the time of
-writing, but there is insufficient testing to provide stability guarantees and
-every expansion of testing has generally revealed new issues. If you do enable
-snapshots and experience failure, manual intervention will be needed.
-
-Snapshots are known not to work properly with multiple file systems (below) in
-some cases. Specifically, if you share a pool for multiple FSes and delete
-a snapshot in one FS, expect to lose snapshotted file data in any other FS using
-snapshots. See the :doc:`/dev/cephfs-snapshots` page for more information.
-
-For somewhat obscure implementation reasons, the kernel client only supports up
-to 400 snapshots (http://tracker.ceph.com/issues/21420).
-
-Snapshotting was blocked off with the ``allow_new_snaps`` flag prior to Mimic.
-
-Multiple File Systems within a Ceph Cluster
--------------------------------------------
-Code was merged prior to the Jewel release which enables administrators
-to create multiple independent CephFS file systems within a single Ceph cluster.
-These independent file systems have their own set of active MDSes, cluster maps,
-and data. But the feature required extensive changes to data structures which
-are not yet fully qualified, and has security implications which are not all
-apparent nor resolved.
-
-There are no known bugs, but any failures which do result from having multiple
-active file systems in your cluster will require manual intervention and, so
-far, will not have been experienced by anybody else -- knowledgeable help will
-be extremely limited. You also probably do not have the security or isolation
-guarantees you want or think you have upon doing so.
-
-Note that snapshots and multiple file systems are *not* tested in combination
-and may not work together; see above.
-
-Multiple file systems were available starting in the Jewel release candidates
-but must be turned on via the ``enable_multiple`` flag until declared stable.
-
LazyIO
------
LazyIO relaxes POSIX semantics. Buffered reads/writes are allowed even when a
file is opened by multiple applications on multiple clients. Applications are
responsible for managing cache coherency themselves.
-
-Previously experimental features
-================================
-
-Directory Fragmentation
------------------------
-
-Directory fragmentation was considered experimental prior to the *Luminous*
-(12.2.x). It is now enabled by default on new file systems. To enable
-directory fragmentation on file systems created with older versions of Ceph,
-set the ``allow_dirfrags`` flag on the file system::
-
- ceph fs set <file system name> allow_dirfrags 1
-
-Multiple active metadata servers
---------------------------------
-
-Prior to the *Luminous* (12.2.x) release, running multiple active metadata
-servers within a single file system was considered experimental. Creating
-multiple active metadata servers is now permitted by default on new
-file systems.
-
-File Systems created with older versions of Ceph still require explicitly
-enabling multiple active metadata servers as follows::
-
- ceph fs set <file system name> allow_multimds 1
-
-Note that the default size of the active mds cluster (``max_mds``) is
-still set to 1 initially.
--- /dev/null
+.. _cephfs-multifs:
+
+Multiple Ceph File Systems
+==========================
+
+
+Beginning with the Pacific release, multiple file system support is stable
+and ready to use. This functionality allows configuring separate file systems
+with full data separation on separate pools.
+
+Existing clusters must set a flag to enable multiple file systems::
+
+ ceph fs flag set enable_multiple true
+
+New Ceph clusters automatically set this.
+
+
+Creating a new Ceph File System
+-------------------------------
+
+The new ``volumes`` plugin interface (see: :doc:`/cephfs/fs-volumes`) automates
+most of the work of configuring a new file system. The "volume" concept is
+simply a new file system. This can be done via::
+
+ ceph fs volume create <fs_name>
+
+Ceph will create the new pools and automate the deployment of new MDS to
+support the new file system. The deployment technology used, e.g. cephadm, will
+also configure the MDS affinity (see: :ref:`mds-join-fs`) of new MDS daemons to
+operate the new file system.
+
+
+Securing access
+---------------
+
+The ``fs authorize`` command allows configuring the client's access to a
+particular file system. See also in :ref:`fs-authorize-multifs`. The client will
+only have visibility of authorized file systems and the Monitors/MDS will
+reject access to clients without authorization.
+
+
+Other Notes
+-----------
+
+Multiple file systems do not share pools. This is particularly important for
+snapshots but also because no measures are in place to prevent duplicate
+inodes. The Ceph commands prevent this dangerous configuration.
+
+Each file system has its own set of MDS ranks. Consequently, each new file
+system requires more MDS daemons to operate and increases operational costs.
+This can be useful for increasing metadata throughput by application or user
+base but also adds cost to the creation of a file system. Generally, a single
+file system with subtree pinning is a better choice for isolating load between
+applications.
projects / ceph.git / commitdiff