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diff --git a/doc/man/8/mount.ceph.rst b/doc/man/8/mount.ceph.rst index fbe8790dd..e45030cd0 100644 --- a/doc/man/8/mount.ceph.rst +++ b/doc/man/8/mount.ceph.rst @@ -199,6 +199,50 @@ Advanced option is enabled, a namespace operation may complete before the MDS replies, if it has sufficient capabilities to do so. +:command:`crush_location=x` + Specify the location of the client in terms of CRUSH hierarchy (since 5.8). + This is a set of key-value pairs separated from each other by '|', with + keys separated from values by ':'. Note that '|' may need to be quoted + or escaped to avoid it being interpreted as a pipe by the shell. The key + is the bucket type name (e.g. rack, datacenter or region with default + bucket types) and the value is the bucket name. For example, to indicate + that the client is local to rack "myrack", data center "mydc" and region + "myregion":: + + crush_location=rack:myrack|datacenter:mydc|region:myregion + + Each key-value pair stands on its own: "myrack" doesn't need to reside in + "mydc", which in turn doesn't need to reside in "myregion". The location + is not a path to the root of the hierarchy but rather a set of nodes that + are matched independently. "Multipath" locations are supported, so it is + possible to indicate locality for multiple parallel hierarchies:: + + crush_location=rack:myrack1|rack:myrack2|datacenter:mydc + + +:command:`read_from_replica=<no|balance|localize>` + - ``no``: Disable replica reads, always pick the primary OSD (since 5.8, default). + + - ``balance``: When a replicated pool receives a read request, pick a random + OSD from the PG's acting set to serve it (since 5.8). + + This mode is safe for general use only since Octopus (i.e. after "ceph osd + require-osd-release octopus"). Otherwise it should be limited to read-only + workloads such as snapshots. + + - ``localize``: When a replicated pool receives a read request, pick the most + local OSD to serve it (since 5.8). The locality metric is calculated against + the location of the client given with crush_location; a match with the + lowest-valued bucket type wins. For example, an OSD in a matching rack + is closer than an OSD in a matching data center, which in turn is closer + than an OSD in a matching region. + + This mode is safe for general use only since Octopus (i.e. after "ceph osd + require-osd-release octopus"). Otherwise it should be limited to read-only + workloads such as snapshots. + + + Examples ======== |