1OSDMAPTOOL(8) Ceph OSDMAPTOOL(8)
2
6 osdmaptool - ceph osd cluster map manipulation tool
7
9 osdmaptool mapfilename [--print] [--createsimple numosd
10 [--pgbits bitsperosd ] ] [--clobber]
11
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.
17
19 --print
20 will simply make the tool print a plaintext dump of the map,
21 after any modifications are made.
22 --dump <format>
24 displays the map in plain text when <format> is 'plain', 'json'
25 if specified format is not supported. This is an alternative to
26 the print option.
27 --clobber
29 will allow osdmaptool to overwrite mapfilename if changes are
30 made.
31 --import-crush mapfile
33 will load the CRUSH map from mapfile and embed it in the OSD
34 map.
35 --export-crush mapfile
37 will extract the CRUSH map from the OSD map and write it to map‐
38 file.
39 --createsimple numosd [--pg-bits bitsperosd] [--pgp-bits bits]
41 will create a relatively generic OSD map with the numosd
42 devices. If --pg-bits is specified, the initial placement group
43 counts will be set with bitsperosd bits per OSD. That is, the
44 pg_num map attribute will be set to numosd shifted by bitsper‐
45 osd. If --pgp-bits is specified, then the pgp_num map attribute
46 will be set to numosd shifted by bits.
47 --create-from-conf
49 creates an osd map with default configurations.
50 --test-map-pgs [--pool poolid] [--range-first <first> --range-last
52 <last>]
53 will print out the mappings from placement groups to OSDs. If
54 range is specified, then it iterates from first to last in the
55 directory specified by argument to osdmaptool. Eg: osdmaptool
56 --test-map-pgs --range-first 0 --range-last 2 osdmap_dir. This
57 will iterate through the files named 0,1,2 in osdmap_dir.
58 --test-map-pgs-dump [--pool poolid] [--range-first <first> --range-last
60 <last>]
61 will print out the summary of all placement groups and the map‐
62 pings from them to the mapped OSDs. If range is specified, then
63 it iterates from first to last in the directory specified by
64 argument to osdmaptool. Eg: osdmaptool --test-map-pgs-dump
65 --range-first 0 --range-last 2 osdmap_dir. This will iterate
66 through the files named 0,1,2 in osdmap_dir.
67 --test-map-pgs-dump-all [--pool poolid] [--range-first <first>
69 --range-last <last>]
70 will print out the summary of all placement groups and the map‐
71 pings from them to all the OSDs. If range is specified, then it
72 iterates from first to last in the directory specified by argu‐
73 ment to osdmaptool. Eg: osdmaptool --test-map-pgs-dump-all
74 --range-first 0 --range-last 2 osdmap_dir. This will iterate
75 through the files named 0,1,2 in osdmap_dir.
76 --test-random
78 does a random mapping of placement groups to the OSDs.
79 --test-map-pg <pgid>
81 map a particular placement group(specified by pgid) to the OSDs.
82 --test-map-object <objectname> [--pool <poolid>]
84 map a particular placement group(specified by objectname) to the
85 OSDs.
86 --test-crush [--range-first <first> --range-last <last>]
88 map placement groups to acting OSDs. If range is specified,
89 then it iterates from first to last in the directory specified
90 by argument to osdmaptool. Eg: osdmaptool --test-crush
91 --range-first 0 --range-last 2 osdmap_dir. This will iterate
92 through the files named 0,1,2 in osdmap_dir.
93 --mark-up-in
95 mark osds up and in (but do not persist).
96 --tree Displays a hierarchical tree of the map.
98 --clear-temp
100 clears pg_temp and primary_temp variables.
101
103 To create a simple map with 16 devices:
104 osdmaptool --createsimple 16 osdmap --clobber
106 To view the result:
108 osdmaptool --print osdmap
110 To view the mappings of placement groups for pool 0:
112 osdmaptool --test-map-pgs-dump rbd --pool 0
114 pool 0 pg_num 8
116 0.0 [0,2,1] 0
117 0.1 [2,0,1] 2
118 0.2 [0,1,2] 0
119 0.3 [2,0,1] 2
120 0.4 [0,2,1] 0
121 0.5 [0,2,1] 0
122 0.6 [0,1,2] 0
123 0.7 [1,0,2] 1
124 #osd count first primary c wt wt
125 osd.0 8 5 5 1 1
126 osd.1 8 1 1 1 1
127 osd.2 8 2 2 1 1
128 in 3
129 avg 8 stddev 0 (0x) (expected 2.3094 0.288675x))
130 min osd.0 8
131 max osd.0 8
132 size 0 0
133 size 1 0
134 size 2 0
135 size 3 8
136 In which,
138 1. pool 0 has 8 placement groups. And two tables follow:
140 2. A table for placement groups. Each row presents a placement
142 group. With columns of:
143 · placement group id,
145 · acting set, and
147 · primary OSD.
149 3. A table for all OSDs. Each row presents an OSD. With columns
151 of:
152 · count of placement groups being mapped to this OSD,
154 · count of placement groups where this OSD is the first one
156 in their acting sets,
157 · count of placement groups where this OSD is the primary of
159 them,
160 · the CRUSH weight of this OSD, and
162 · the weight of this OSD.
164 4. Looking at the number of placement groups held by 3 OSDs. We
166 have
167 · avarge, stddev, stddev/average, expected stddev, expected
169 stddev / average
170 · min and max
172 5. The number of placement groups mapping to n OSDs. In this
174 case, all 8 placement groups are mapping to 3 different OSDs.
175 In a less-balanced cluster, we could have following output for the sta‐
177 tistics of placement group distribution, whose standard deviation is
178 1.41421:
179 #osd count first primary c wt wt
181 osd.0 8 5 5 1 1
182 osd.1 8 1 1 1 1
183 osd.2 8 2 2 1 1
184 #osd count first primary c wt wt
186 osd.0 33 9 9 0.0145874 1
187 osd.1 34 14 14 0.0145874 1
188 osd.2 31 7 7 0.0145874 1
189 osd.3 31 13 13 0.0145874 1
190 osd.4 30 14 14 0.0145874 1
191 osd.5 33 7 7 0.0145874 1
192 in 6
193 avg 32 stddev 1.41421 (0.0441942x) (expected 5.16398 0.161374x))
194 min osd.4 30
195 max osd.1 34
196 size 00
197 size 10
198 size 20
199 size 364
200
202 osdmaptool is part of Ceph, a massively scalable, open-source, distrib‐
203 uted storage system. Please refer to the Ceph documentation at
204 http://ceph.com/docs for more information.
205
207 ceph(8), crushtool(8),
208
210 2010-2014, Inktank Storage, Inc. and contributors. Licensed under Cre‐
211 ative Commons Attribution Share Alike 3.0 (CC-BY-SA-3.0)
212dev Apr 29, 2019 OSDMAPTOOL(8)