--- /dev/null
+:orphan:
+
+======================================================
+ osdmaptool -- ceph osd cluster map manipulation tool
+======================================================
+
+.. program:: osdmaptool
+
+Synopsis
+========
+
+| **osdmaptool** *mapfilename* [--print] [--createsimple *numosd*
+ [--pgbits *bitsperosd* ] ] [--clobber]
+
+
+Description
+===========
+
+**osdmaptool** is a utility that lets you create, view, and manipulate
+OSD cluster maps from the Ceph distributed storage system. Notably, it
+lets you extract the embedded CRUSH map or import a new CRUSH map.
+
+
+Options
+=======
+
+.. option:: --print
+
+ will simply make the tool print a plaintext dump of the map, after
+ any modifications are made.
+
+.. option:: --clobber
+
+ will allow osdmaptool to overwrite mapfilename if changes are made.
+
+.. option:: --import-crush mapfile
+
+ will load the CRUSH map from mapfile and embed it in the OSD map.
+
+.. option:: --export-crush mapfile
+
+ will extract the CRUSH map from the OSD map and write it to
+ mapfile.
+
+.. option:: --createsimple numosd [--pgbits bitsperosd]
+
+ will create a relatively generic OSD map with the numosd devices.
+ If --pgbits is specified, the initial placement group counts will
+ be set with bitsperosd bits per OSD. That is, the pg_num map
+ attribute will be set to numosd shifted by bitsperosd.
+
+.. option:: --test-map-pgs [--pool poolid]
+
+ will print out the mappings from placement groups to OSDs.
+
+.. option:: --test-map-pgs-dump [--pool poolid]
+
+ will print out the summary of all placement groups and the mappings
+ from them to the mapped OSDs.
+
+
+Example
+=======
+
+To create a simple map with 16 devices::
+
+ osdmaptool --createsimple 16 osdmap --clobber
+
+To view the result::
+
+ osdmaptool --print osdmap
+
+To view the mappings of placement groups for pool 0::
+
+ osdmaptool --test-map-pgs-dump rbd --pool 0
+
+ pool 0 pg_num 8
+ 0.0 [0,2,1] 0
+ 0.1 [2,0,1] 2
+ 0.2 [0,1,2] 0
+ 0.3 [2,0,1] 2
+ 0.4 [0,2,1] 0
+ 0.5 [0,2,1] 0
+ 0.6 [0,1,2] 0
+ 0.7 [1,0,2] 1
+ #osd count first primary c wt wt
+ osd.0 8 5 5 1 1
+ osd.1 8 1 1 1 1
+ osd.2 8 2 2 1 1
+ in 3
+ avg 8 stddev 0 (0x) (expected 2.3094 0.288675x))
+ min osd.0 8
+ max osd.0 8
+ size 0 0
+ size 1 0
+ size 2 0
+ size 3 8
+
+In which,
+ #. pool 0 has 8 placement groups. And two tables follow:
+ #. A table for placement groups. Each row presents a placement group. With columns of:
+
+ * placement group id,
+ * acting set, and
+ * primary OSD.
+ #. A table for all OSDs. Each row presents an OSD. With columns of:
+
+ * count of placement groups being mapped to this OSD,
+ * count of placement groups where this OSD is the first one in their acting sets,
+ * count of placement groups where this OSD is the primary of them,
+ * the CRUSH weight of this OSD, and
+ * the weight of this OSD.
+ #. Looking at the number of placement groups held by 3 OSDs. We have
+
+ * avarge, stddev, stddev/average, expected stddev, expected stddev / average
+ * min and max
+ #. The number of placement groups mapping to n OSDs. In this case, all 8 placement
+ groups are mapping to 3 different OSDs.
+
+In a less-balanced cluster, we could have following output for the statistics of
+placement group distribution, whose standard deviation is 1.41421::
+
+ #osd count first primary c wt wt
+ osd.0 8 5 5 1 1
+ osd.1 8 1 1 1 1
+ osd.2 8 2 2 1 1
+
+ #osd count first primary c wt wt
+ osd.0 33 9 9 0.0145874 1
+ osd.1 34 14 14 0.0145874 1
+ osd.2 31 7 7 0.0145874 1
+ osd.3 31 13 13 0.0145874 1
+ osd.4 30 14 14 0.0145874 1
+ osd.5 33 7 7 0.0145874 1
+ in 6
+ avg 32 stddev 1.41421 (0.0441942x) (expected 5.16398 0.161374x))
+ min osd.4 30
+ max osd.1 34
+ size 00
+ size 10
+ size 20
+ size 364
+
+
+Availability
+============
+
+**osdmaptool** is part of Ceph, a massively scalable, open-source, distributed storage system. Please
+refer to the Ceph documentation at http://ceph.com/docs for more
+information.
+
+
+See also
+========
+
+:doc:`ceph <ceph>`\(8),
+:doc:`crushtool <crushtool>`\(8),
Code Review / stor4nfv.git / blobdiff