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.TH "OSDMAPTOOL" "8" "Mar 03, 2019" "dev" "Ceph"
.SH NAME
osdmaptool \- ceph osd cluster map manipulation tool
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.SH SYNOPSIS
.nf
\fBosdmaptool\fP \fImapfilename\fP [\-\-print] [\-\-createsimple \fInumosd\fP
[\-\-pgbits \fIbitsperosd\fP ] ] [\-\-clobber]
.fi
.sp
.SH DESCRIPTION
.sp
\fBosdmaptool\fP 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.
.SH OPTIONS
.INDENT 0.0
.TP
.B \-\-print
will simply make the tool print a plaintext dump of the map, after
any modifications are made.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-clobber
will allow osdmaptool to overwrite mapfilename if changes are made.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-import\-crush mapfile
will load the CRUSH map from mapfile and embed it in the OSD map.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-export\-crush mapfile
will extract the CRUSH map from the OSD map and write it to
mapfile.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-createsimple numosd [\-\-pgbits bitsperosd]
will create a relatively generic OSD map with the numosd devices.
If \-\-pgbits 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.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-test\-map\-pgs [\-\-pool poolid]
will print out the mappings from placement groups to OSDs.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-test\-map\-pgs\-dump [\-\-pool poolid]
will print out the summary of all placement groups and the mappings
from them to the mapped OSDs.
.UNINDENT
.SH EXAMPLE
.sp
To create a simple map with 16 devices:
.INDENT 0.0
.INDENT 3.5
.sp
.nf
.ft C
osdmaptool \-\-createsimple 16 osdmap \-\-clobber
.ft P
.fi
.UNINDENT
.UNINDENT
.sp
To view the result:
.INDENT 0.0
.INDENT 3.5
.sp
.nf
.ft C
osdmaptool \-\-print osdmap
.ft P
.fi
.UNINDENT
.UNINDENT
.sp
To view the mappings of placement groups for pool 0:
.INDENT 0.0
.INDENT 3.5
.sp
.nf
.ft C
osdmaptool \-\-test\-map\-pgs\-dump rbd \-\-pool 0

pool 0 pg_num 8
0.0     [0,2,1] 0
0.1     [2,0,1] 2
0.2     [0,1,2] 0
0.3     [2,0,1] 2
0.4     [0,2,1] 0
0.5     [0,2,1] 0
0.6     [0,1,2] 0
0.7     [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
.ft P
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.UNINDENT
.UNINDENT
.INDENT 0.0
.TP
.B In which,
.INDENT 7.0
.IP 1. 3
pool 0 has 8 placement groups. And two tables follow:
.IP 2. 3
A table for placement groups. Each row presents a placement group. With columns of:
.INDENT 3.0
.IP \(bu 2
placement group id,
.IP \(bu 2
acting set, and
.IP \(bu 2
primary OSD.
.UNINDENT
.IP 3. 3
A table for all OSDs. Each row presents an OSD. With columns of:
.INDENT 3.0
.IP \(bu 2
count of placement groups being mapped to this OSD,
.IP \(bu 2
count of placement groups where this OSD is the first one in their acting sets,
.IP \(bu 2
count of placement groups where this OSD is the primary of them,
.IP \(bu 2
the CRUSH weight of this OSD, and
.IP \(bu 2
the weight of this OSD.
.UNINDENT
.IP 4. 3
Looking at the number of placement groups held by 3 OSDs. We have
.INDENT 3.0
.IP \(bu 2
avarge, stddev, stddev/average, expected stddev, expected stddev / average
.IP \(bu 2
min and max
.UNINDENT
.IP 5. 3
The number of placement groups mapping to n OSDs. In this case, all 8 placement
groups are mapping to 3 different OSDs.
.UNINDENT
.UNINDENT
.sp
In a less\-balanced cluster, we could have following output for the statistics of
placement group distribution, whose standard deviation is 1.41421:
.INDENT 0.0
.INDENT 3.5
.sp
.nf
.ft C
#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
.ft P
.fi
.UNINDENT
.UNINDENT
.SH AVAILABILITY
.sp
\fBosdmaptool\fP is part of Ceph, a massively scalable, open\-source, distributed storage system.  Please
refer to the Ceph documentation at \fI\%http://ceph.com/docs\fP for more
information.
.SH SEE ALSO
.sp
ceph(8),
crushtool(8),
.SH COPYRIGHT
2010-2019, Inktank Storage, Inc. and contributors. Licensed under Creative Commons Attribution Share Alike 3.0 (CC-BY-SA-3.0)
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