ceph/doc/man/8/osdmaptool.rst

   1 :orphan:
   2
   3 ======================================================
   4  osdmaptool -- ceph osd cluster map manipulation tool
   5 ======================================================
   6
   7 .. program:: osdmaptool
   8
   9 Synopsis
  10 ========
  11
  12 | **osdmaptool** *mapfilename* [--print] [--createsimple *numosd*
  13   [--pgbits *bitsperosd* ] ] [--clobber]
  14
  15
  16 Description
  17 ===========
  18
  19 **osdmaptool** is a utility that lets you create, view, and manipulate
  20 OSD cluster maps from the Ceph distributed storage system. Notably, it
  21 lets you extract the embedded CRUSH map or import a new CRUSH map.
  22
  23
  24 Options
  25 =======
  26
  27 .. option:: --print
  28
  29    will simply make the tool print a plaintext dump of the map, after
  30    any modifications are made.
  31
  32 .. option:: --clobber
  33
  34    will allow osdmaptool to overwrite mapfilename if changes are made.
  35
  36 .. option:: --import-crush mapfile
  37
  38    will load the CRUSH map from mapfile and embed it in the OSD map.
  39
  40 .. option:: --export-crush mapfile
  41
  42    will extract the CRUSH map from the OSD map and write it to
  43    mapfile.
  44
  45 .. option:: --createsimple numosd [--pgbits bitsperosd]
  46
  47    will create a relatively generic OSD map with the numosd devices.
  48    If --pgbits is specified, the initial placement group counts will
  49    be set with bitsperosd bits per OSD. That is, the pg_num map
  50    attribute will be set to numosd shifted by bitsperosd.
  51
  52 .. option:: --test-map-pgs [--pool poolid]
  53
  54    will print out the mappings from placement groups to OSDs.
  55
  56 .. option:: --test-map-pgs-dump [--pool poolid]
  57
  58    will print out the summary of all placement groups and the mappings
  59    from them to the mapped OSDs.
  60
  61
  62 Example
  63 =======
  64
  65 To create a simple map with 16 devices::
  66
  67         osdmaptool --createsimple 16 osdmap --clobber
  68
  69 To view the result::
  70
  71         osdmaptool --print osdmap
  72
  73 To view the mappings of placement groups for pool 0::
  74
  75         osdmaptool --test-map-pgs-dump rbd --pool 0
  76
  77         pool 0 pg_num 8
  78         0.0     [0,2,1] 0
  79         0.1     [2,0,1] 2
  80         0.2     [0,1,2] 0
  81         0.3     [2,0,1] 2
  82         0.4     [0,2,1] 0
  83         0.5     [0,2,1] 0
  84         0.6     [0,1,2] 0
  85         0.7     [1,0,2] 1
  86         #osd    count   first   primary c wt    wt
  87         osd.0   8       5       5       1       1
  88         osd.1   8       1       1       1       1
  89         osd.2   8       2       2       1       1
  90          in 3
  91          avg 8 stddev 0 (0x) (expected 2.3094 0.288675x))
  92          min osd.0 8
  93          max osd.0 8
  94         size 0  0
  95         size 1  0
  96         size 2  0
  97         size 3  8
  98
  99 In which,
 100  #. pool 0 has 8 placement groups. And two tables follow:
 101  #. A table for placement groups. Each row presents a placement group. With columns of:
 102
 103     * placement group id,
 104     * acting set, and
 105     * primary OSD.
 106  #. A table for all OSDs. Each row presents an OSD. With columns of:
 107
 108     * count of placement groups being mapped to this OSD,
 109     * count of placement groups where this OSD is the first one in their acting sets,
 110     * count of placement groups where this OSD is the primary of them,
 111     * the CRUSH weight of this OSD, and
 112     * the weight of this OSD.
 113  #. Looking at the number of placement groups held by 3 OSDs. We have
 114
 115     * avarge, stddev, stddev/average, expected stddev, expected stddev / average
 116     * min and max
 117  #. The number of placement groups mapping to n OSDs. In this case, all 8 placement
 118     groups are mapping to 3 different OSDs.
 119
 120 In a less-balanced cluster, we could have following output for the statistics of
 121 placement group distribution, whose standard deviation is 1.41421::
 122
 123         #osd    count   first   primary c wt    wt
 124         osd.0   8       5       5       1       1
 125         osd.1   8       1       1       1       1
 126         osd.2   8       2       2       1       1
 127
 128         #osd    count   first    primary c wt    wt
 129         osd.0   33      9        9       0.0145874     1
 130         osd.1   34      14       14      0.0145874     1
 131         osd.2   31      7        7       0.0145874     1
 132         osd.3   31      13       13      0.0145874     1
 133         osd.4   30      14       14      0.0145874     1
 134         osd.5   33      7        7       0.0145874     1
 135          in 6
 136          avg 32 stddev 1.41421 (0.0441942x) (expected 5.16398 0.161374x))
 137          min osd.4 30
 138          max osd.1 34
 139         size 00
 140         size 10
 141         size 20
 142         size 364
 143
 144
 145 Availability
 146 ============
 147
 148 **osdmaptool** is part of Ceph, a massively scalable, open-source, distributed storage system.  Please
 149 refer to the Ceph documentation at http://ceph.com/docs for more
 150 information.
 151
 152
 153 See also
 154 ========
 155
 156 :doc:`ceph <ceph>`\(8),
 157 :doc:`crushtool <crushtool>`\(8),