OSDMAPTOOL(8)

NAME
osdmaptool - ceph osd cluster map manipulation tool

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

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

--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.

--clobber
    will allow osdmaptool to overwrite mapfilename if changes are made.

--import-crush mapfile
    will load the CRUSH map from mapfile and embed it in the OSD map.

--export-crush mapfile
    will extract the CRUSH map from the OSD map and write it to mapfile.

--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.

--create-from-conf
    creates an osd map with default configurations.

--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.

--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.

--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.

--test-random
    does a random mapping of placement groups to the OSDs.

--test-map-pg <pgid>
    map a particular placement group(specified by pgid) to the OSDs.

--test-map-object <objectname> [--pool <poolid>]
    map a particular placement group(specified by objectname) to the OSDs.

--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.

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

--mark-out
    mark an osd as out (but do not persist)

--tree
    Displays a hierarchical tree of the map.

--clear-temp
    clears pg_temp and primary_temp variables.

--clean-temps
    clean pg_temps.

--health
    dump health checks

--with-default-pool
    include default pool when creating map

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

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

--upmap-max <max-optimizations>
    set max upmap entries to calculate [default: 10]

--upmap-deviation <max-deviation>
    max deviation from target [default: 5]

--upmap-pool <poolname>
    restrict upmap balancing to 1 pool or the option can be repeated for multiple pools

--upmap-save
    write modified OSDMap with upmap changes

--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,

1.  pool 1 has 8 placement groups. And two tables follow:

2.  A table for placement groups. Each row presents a placement group. With columns of:

•   placement group id,

•   acting set, and

•   primary OSD.

3.  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.

4.  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

5.  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

ceph(8), crushtool(8),

COPYRIGHT
2010-2022, Inktank Storage, Inc. and contributors. Licensed under Creative Commons Attribution Share Alike 3.0 (CC-BY-SA-3.0)