Adding upstream version 16.2.11+ds.upstream/16.2.11+dsupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 42 insertions, 0 deletions

diff --git a/doc/cephfs/experimental-features.rst b/doc/cephfs/experimental-features.rst
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+=====================
+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.
+
+Inline data has been declared deprecated for the Octopus release, and will
+likely be removed altogether in the Q release.
+
+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`.
+
+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.