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OSDMAPTOOL(8) Ceph 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]
[--save] [--upmap-active]
osdmaptool mapfilename [--upmap-cleanup] [--upmap file]

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

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

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.

will allow osdmaptool to overwrite mapfilename if changes are made.

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

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

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.

creates an osd map with default configurations.

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.

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.

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.

does a random mapping of placement groups to the OSDs.

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

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

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 osds up and in (but do not persist).

mark an osd as out (but do not persist)

mark an osd as up (but do not persist)

mark an osd as in (but do not persist)

Displays a hierarchical tree of the map.

clears pg_temp and primary_temp variables.

clean pg_temps.

dump health checks

include default pool when creating map

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

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

set max upmap entries to calculate [default: 10]

max deviation from target [default: 5]

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

Act like an active balancer, keep applying changes until balanced


write modified osdmap with upmap or crush-adjust changes

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 1 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


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

2010-2023, Inktank Storage, Inc. and contributors. Licensed under Creative Commons Attribution Share Alike 3.0 (CC-BY-SA-3.0)

February 16, 2023 dev