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43 lines
1.8 KiB
ReStructuredText
43 lines
1.8 KiB
ReStructuredText
=====================
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Experimental Features
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=====================
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CephFS includes a number of experimental features which are not fully
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stabilized or qualified for users to turn on in real deployments. We generally
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do our best to clearly demarcate these and fence them off so they cannot be
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used by mistake.
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Some of these features are closer to being done than others, though. We
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describe each of them with an approximation of how risky they are and briefly
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describe what is required to enable them. Note that doing so will
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*irrevocably* flag maps in the monitor as having once enabled this flag to
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improve debugging and support processes.
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Inline data
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-----------
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By default, all CephFS file data is stored in RADOS objects. The inline data
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feature enables small files (generally <2KB) to be stored in the inode
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and served out of the MDS. This may improve small-file performance but increases
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load on the MDS. It is not sufficiently tested to support at this time, although
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failures within it are unlikely to make non-inlined data inaccessible
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Inline data has always been off by default and requires setting
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the ``inline_data`` flag.
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Inline data has been declared deprecated for the Octopus release, and will
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likely be removed altogether in the Q release.
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Mantle: Programmable Metadata Load Balancer
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-------------------------------------------
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Mantle is a programmable metadata balancer built into the MDS. The idea is to
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protect the mechanisms for balancing load (migration, replication,
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fragmentation) but stub out the balancing policies using Lua. For details, see
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:doc:`/cephfs/mantle`.
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LazyIO
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------
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LazyIO relaxes POSIX semantics. Buffered reads/writes are allowed even when a
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file is opened by multiple applications on multiple clients. Applications are
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responsible for managing cache coherency themselves.
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