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.. _osdmaptool:

======================================================
 osdmaptool -- ceph osd cluster map manipulation tool
======================================================

.. program:: osdmaptool

Synopsis
========

| **osdmaptool** *mapfilename* [--print] [--createsimple *numosd*
  [--pgbits *bitsperosd* ] ] [--clobber]
| **osdmaptool** *mapfilename* [--import-crush *crushmap*]
| **osdmaptool** *mapfilename* [--export-crush *crushmap*]
| **osdmaptool** *mapfilename* [--upmap *file*] [--upmap-max *max-optimizations*]
  [--upmap-deviation *max-deviation*] [--upmap-pool *poolname*]
  [--upmap-save *file*] [--upmap-save *newosdmap*] [--upmap-active]
| **osdmaptool** *mapfilename* [--upmap-cleanup] [--upmap-save *newosdmap*]


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.
It can also simulate the upmap balancer mode so you can get a sense of
what is needed to balance your PGs.


Options
=======

.. option:: --print

   will simply make the tool print a plaintext dump of the map, after
   any modifications are made.

.. option:: --dump <format>

   displays the map in plain text when <format> is 'plain', 'json' if specified
   format is not supported. This is an alternative to the print option.

.. 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 [--pg-bits bitsperosd] [--pgp-bits bits]

   will create a relatively generic OSD map with the numosd devices.
   If --pg-bits 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.
   If --pgp-bits is specified, then the pgp_num map attribute will
   be set to numosd shifted by bits. 

.. option:: --create-from-conf

   creates an osd map with default configurations.

.. option:: --test-map-pgs [--pool poolid] [--range-first <first> --range-last <last>]

   will print out the mappings from placement groups to OSDs.
   If range is specified, then it iterates from first to last in the directory 
   specified by argument to osdmaptool.
   Eg: **osdmaptool --test-map-pgs --range-first 0 --range-last 2 osdmap_dir**.
   This will iterate through the files named 0,1,2 in osdmap_dir.

.. option:: --test-map-pgs-dump [--pool poolid] [--range-first <first> --range-last <last>]

   will print out the summary of all placement groups and the mappings from them to the mapped OSDs.
   If range is specified, then it iterates from first to last in the directory
   specified by argument to osdmaptool.
   Eg: **osdmaptool --test-map-pgs-dump --range-first 0 --range-last 2 osdmap_dir**.
   This will iterate through the files named 0,1,2 in osdmap_dir.

.. option:: --test-map-pgs-dump-all [--pool poolid] [--range-first <first> --range-last <last>]

   will print out the summary of all placement groups and the mappings
   from them to all the OSDs.
   If range is specified, then it iterates from first to last in the directory
   specified by argument to osdmaptool.
   Eg: **osdmaptool --test-map-pgs-dump-all --range-first 0 --range-last 2 osdmap_dir**.
   This will iterate through the files named 0,1,2 in osdmap_dir.

.. option:: --test-random

   does a random mapping of placement groups to the OSDs.

.. option:: --test-map-pg <pgid>

   map a particular placement group(specified by pgid) to the OSDs.

.. option:: --test-map-object <objectname> [--pool <poolid>]

   map a particular placement group(specified by objectname) to the OSDs.

.. option:: --test-crush [--range-first <first> --range-last <last>]

   map placement groups to acting OSDs.
   If range is specified, then it iterates from first to last in the directory
   specified by argument to osdmaptool.
   Eg: **osdmaptool --test-crush --range-first 0 --range-last 2 osdmap_dir**.
   This will iterate through the files named 0,1,2 in osdmap_dir.

.. option:: --mark-up-in

   mark osds up and in (but do not persist).

.. option:: --mark-out

   mark an osd as out (but do not persist)

.. option:: --tree

   Displays a hierarchical tree of the map.

.. option:: --clear-temp

   clears pg_temp and primary_temp variables.

.. option:: --health

   dump health checks

.. option:: --with-default-pool

   include default pool when creating map

.. option:: --upmap-cleanup <file>

   clean up pg_upmap[_items] entries, writing commands to <file> [default: - for stdout]

.. option:: --upmap <file>

   calculate pg upmap entries to balance pg layout writing commands to <file> [default: - for stdout]

.. option:: --upmap-max <max-optimizations>

   set max upmap entries to calculate [default: 10]

.. option:: --upmap-deviation <max-deviation>

   max deviation from target [default: 5]

.. option:: --upmap-pool <poolname>

   restrict upmap balancing to 1 pool or the option can be repeated for multiple pools

.. option:: --upmap-save

   write modified OSDMap with upmap changes

.. option:: --upmap-active

   Act like an active balancer, keep applying changes until balanced


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 1::

        osdmaptool osdmap --test-map-pgs-dump --pool 1

        pool 0 pg_num 8
        1.0     [0,2,1] 0
        1.1     [2,0,1] 2
        1.2     [0,1,2] 0
        1.3     [2,0,1] 2
        1.4     [0,2,1] 0
        1.5     [0,2,1] 0
        1.6     [0,1,2] 0
        1.7     [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 1 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

   To simulate the active balancer in upmap mode::

        osdmaptool --upmap upmaps.out --upmap-active --upmap-deviation 6 --upmap-max 11 osdmap

   osdmaptool: osdmap file 'osdmap'
   writing upmap command output to: upmaps.out
   checking for upmap cleanups
   upmap, max-count 11, max deviation 6
   pools movies photos metadata data
   prepared 11/11 changes
   Time elapsed 0.00310404 secs
   pools movies photos metadata data
   prepared 11/11 changes
   Time elapsed 0.00283402 secs
   pools data metadata movies photos
   prepared 11/11 changes
   Time elapsed 0.003122 secs
   pools photos metadata data movies
   prepared 11/11 changes
   Time elapsed 0.00324372 secs
   pools movies metadata data photos
   prepared 1/11 changes
   Time elapsed 0.00222609 secs
   pools data movies photos metadata
   prepared 0/11 changes
   Time elapsed 0.00209916 secs
   Unable to find further optimization, or distribution is already perfect
   osd.0 pgs 41
   osd.1 pgs 42
   osd.2 pgs 42
   osd.3 pgs 41
   osd.4 pgs 46
   osd.5 pgs 39
   osd.6 pgs 39
   osd.7 pgs 43
   osd.8 pgs 41
   osd.9 pgs 46
   osd.10 pgs 46
   osd.11 pgs 46
   osd.12 pgs 46
   osd.13 pgs 41
   osd.14 pgs 40
   osd.15 pgs 40
   osd.16 pgs 39
   osd.17 pgs 46
   osd.18 pgs 46
   osd.19 pgs 39
   osd.20 pgs 42
   Total time elapsed 0.0167765 secs, 5 rounds


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),