osdmaptool(8)

1OSDMAPTOOL(8)                        Ceph                        OSDMAPTOOL(8)
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NAME

6       osdmaptool - ceph osd cluster map manipulation tool
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SYNOPSIS

9       osdmaptool mapfilename [--print] [--createsimple numosd
10       [--pgbits bitsperosd ] ] [--clobber]
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12

DESCRIPTION

14       osdmaptool  is a utility that lets you create, view, and manipulate OSD
15       cluster maps from the Ceph distributed storage system. Notably, it lets
16       you extract the embedded CRUSH map or import a new CRUSH map.
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OPTIONS

19       --print
20              will  simply  make  the  tool print a plaintext dump of the map,
21              after any modifications are made.
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23       --clobber
24              will allow osdmaptool to overwrite mapfilename  if  changes  are
25              made.
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27       --import-crush mapfile
28              will  load  the  CRUSH  map from mapfile and embed it in the OSD
29              map.
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31       --export-crush mapfile
32              will extract the CRUSH map from the OSD map and write it to map‐
33              file.
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35       --createsimple numosd [--pgbits bitsperosd]
36              will  create  a  relatively  generic  OSD  map  with  the numosd
37              devices.  If --pgbits is specified, the initial placement  group
38              counts  will  be  set with bitsperosd bits per OSD. That is, the
39              pg_num map attribute will be set to numosd shifted  by  bitsper‐
40              osd.
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42       --test-map-pgs [--pool poolid]
43              will print out the mappings from placement groups to OSDs.
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45       --test-map-pgs-dump [--pool poolid]
46              will  print out the summary of all placement groups and the map‐
47              pings from them to the mapped OSDs.
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EXAMPLE

50       To create a simple map with 16 devices:
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52          osdmaptool --createsimple 16 osdmap --clobber
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54       To view the result:
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56          osdmaptool --print osdmap
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58       To view the mappings of placement groups for pool 0:
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60          osdmaptool --test-map-pgs-dump rbd --pool 0
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62          pool 0 pg_num 8
63          0.0     [0,2,1] 0
64          0.1     [2,0,1] 2
65          0.2     [0,1,2] 0
66          0.3     [2,0,1] 2
67          0.4     [0,2,1] 0
68          0.5     [0,2,1] 0
69          0.6     [0,1,2] 0
70          0.7     [1,0,2] 1
71          #osd    count   first   primary c wt    wt
72          osd.0   8       5       5       1       1
73          osd.1   8       1       1       1       1
74          osd.2   8       2       2       1       1
75           in 3
76           avg 8 stddev 0 (0x) (expected 2.3094 0.288675x))
77           min osd.0 8
78           max osd.0 8
79          size 0  0
80          size 1  0
81          size 2  0
82          size 3  8
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84       In which,
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86              1. pool 0 has 8 placement groups. And two tables follow:
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88              2. A table for placement groups. Each row presents  a  placement
89                 group. With columns of:
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91                 · placement group id,
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93                 · acting set, and
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95                 · primary OSD.
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97              3. A  table for all OSDs. Each row presents an OSD. With columns
98                 of:
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100                 · count of placement groups being mapped to this OSD,
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102                 · count of placement groups where this OSD is the  first  one
103                   in their acting sets,
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105                 · count  of placement groups where this OSD is the primary of
106                   them,
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108                 · the CRUSH weight of this OSD, and
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110                 · the weight of this OSD.
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112              4. Looking at the number of placement groups held by 3 OSDs.  We
113                 have
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115                 · avarge,  stddev,  stddev/average, expected stddev, expected
116                   stddev / average
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118                 · min and max
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120              5. The number of placement groups mapping to  n  OSDs.  In  this
121                 case, all 8 placement groups are mapping to 3 different OSDs.
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123       In a less-balanced cluster, we could have following output for the sta‐
124       tistics of placement group distribution, whose  standard  deviation  is
125       1.41421:
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127          #osd    count   first   primary c wt    wt
128          osd.0   8       5       5       1       1
129          osd.1   8       1       1       1       1
130          osd.2   8       2       2       1       1
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132          #osd    count   first    primary c wt    wt
133          osd.0   33      9        9       0.0145874     1
134          osd.1   34      14       14      0.0145874     1
135          osd.2   31      7        7       0.0145874     1
136          osd.3   31      13       13      0.0145874     1
137          osd.4   30      14       14      0.0145874     1
138          osd.5   33      7        7       0.0145874     1
139           in 6
140           avg 32 stddev 1.41421 (0.0441942x) (expected 5.16398 0.161374x))
141           min osd.4 30
142           max osd.1 34
143          size 00
144          size 10
145          size 20
146          size 364
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AVAILABILITY

149       osdmaptool is part of Ceph, a massively scalable, open-source, distrib‐
150       uted storage  system.   Please  refer  to  the  Ceph  documentation  at
151       http://ceph.com/docs for more information.
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COPYRIGHT

157       2010-2014,  Inktank Storage, Inc. and contributors. Licensed under Cre‐
158       ative Commons Attribution Share Alike 3.0 (CC-BY-SA-3.0)
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163dev                              Apr 14, 2019                    OSDMAPTOOL(8)