X-Git-Url: https://gerrit.opnfv.org/gerrit/gitweb?a=blobdiff_plain;f=src%2Fceph%2Fdoc%2Fcephfs%2Fexperimental-features.rst;fp=src%2Fceph%2Fdoc%2Fcephfs%2Fexperimental-features.rst;h=0000000000000000000000000000000000000000;hb=7da45d65be36d36b880cc55c5036e96c24b53f00;hp=1dc781a11f05b778d052cc0dc3c0e903286dc16f;hpb=691462d09d0987b47e112d6ee8740375df3c51b2;p=stor4nfv.git diff --git a/src/ceph/doc/cephfs/experimental-features.rst b/src/ceph/doc/cephfs/experimental-features.rst deleted file mode 100644 index 1dc781a..0000000 --- a/src/ceph/doc/cephfs/experimental-features.rst +++ /dev/null @@ -1,107 +0,0 @@ - -Experimental Features -===================== - -CephFS includes a number of experimental features which are not fully stabilized -or qualified for users to turn on in real deployments. We generally do our best -to clearly demarcate these and fence them off so they cannot be used by mistake. - -Some of these features are closer to being done than others, though. We describe -each of them with an approximation of how risky they are and briefly describe -what is required to enable them. Note that doing so will *irrevocably* flag maps -in the monitor as having once enabled this flag to improve debugging and -support processes. - -Inline data ------------ -By default, all CephFS file data is stored in RADOS objects. The inline data -feature enables small files (generally <2KB) to be stored in the inode -and served out of the MDS. This may improve small-file performance but increases -load on the MDS. It is not sufficiently tested to support at this time, although -failures within it are unlikely to make non-inlined data inaccessible - -Inline data has always been off by default and requires setting -the "inline_data" flag. - - - -Mantle: Programmable Metadata Load Balancer -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -Mantle is a programmable metadata balancer built into the MDS. The idea is to -protect the mechanisms for balancing load (migration, replication, -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 filesystems (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. - -Snapshots are known not to work with multi-MDS filesystems. - -Snapshotting was blocked off with the "allow_new_snaps" flag prior to Firefly. - -Multiple filesystems within a Ceph cluster ------------------------------------------- -Code was merged prior to the Jewel release which enables administrators -to create multiple independent CephFS filesystems within a single Ceph cluster. -These independent filesystems 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 filesystems 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 filesystems are *not* tested in combination -and may not work together; see above. - -Multiple filesystems were available starting in the Jewel release candidates -but were protected behind the "enable_multiple" flag before the final release. - - -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 filesystems. To enable directory -fragmentation on filesystems created with older versions of Ceph, set -the ``allow_dirfrags`` flag on the filesystem: - -:: - - ceph fs set allow_dirfrags - -Multiple active metadata servers --------------------------------- - -Prior to the *Luminous* (12.2.x) release, running multiple active metadata -servers within a single filesystem was considered experimental. Creating -multiple active metadata servers is now permitted by default on new -filesystems. - -Filesystems created with older versions of Ceph still require explicitly -enabling multiple active metadata servers as follows: - -:: - - ceph fs set allow_multimds - -Note that the default size of the active mds cluster (``max_mds``) is -still set to 1 initially. -