LUDOC-293 protocol: Merge all recent patches

[doc/protocol.git] / ost_statfs.txt

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+Command 13: OST_STATFS
+~~~~~~~~~~~~~~~~~~~~~~
+[[ost-statfs-rpc]]
+
+OST_STATFS ('pb_opc' = 13) is an RPC that queries data about the
+underlying file system for a given OST. It's form and use are nearly
+identical to the MDS_STATFS RPC. Refer to <<mds-statfs-rpc>> for
+details. The only differences in OST_STATFS are that it has a distinct
+'pb_opc' value, it carries information about an OST (instead of an
+MDT), and it can be generated in this one additional way:  There is a
+regularly scheduled process that 'pings' each OST from each MDT using
+OST_STATFS, so that the MDT can remain current on the available space
+on the OSTs.
+