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: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),
|
