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156 lines
3.7 KiB
Groff
156 lines
3.7 KiB
Groff
.TH "CRUSHTOOL" "8" "September 27, 2012" "dev" "Ceph"
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.SH NAME
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crushtool \- CRUSH map manipulation tool
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.\" Man page generated from reStructuredText.
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.
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.SH SYNOPSIS
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.nf
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\fBcrushtool\fP ( \-d \fImap\fP | \-c \fImap.txt\fP | \-\-build \fInumosds\fP
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\fIlayer1\fP \fI...\fP ) [ \-o \fIoutfile\fP [ \-\-clobber ]]
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.fi
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.sp
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.SH DESCRIPTION
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.sp
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\fBcrushtool\fP is a utility that lets you create, compile, and
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decompile CRUSH map files.
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.sp
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CRUSH is a pseudo\-random data distribution algorithm that efficiently
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maps input values (typically data objects) across a heterogeneous,
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hierarchically structured device map. The algorithm was originally
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described in detail in the following paper (although it has evolved
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some since then):
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.INDENT 0.0
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.INDENT 3.5
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\fI\%http://www.ssrc.ucsc.edu/Papers/weil-sc06.pdf\fP
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.UNINDENT
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.UNINDENT
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.sp
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The tool has four modes of operation.
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.INDENT 0.0
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.TP
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.B \-c map.txt
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will compile a plaintext map.txt into a binary map file.
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.UNINDENT
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.INDENT 0.0
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.TP
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.B \-d map
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will take the compiled map and decompile it into a plaintext source
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file, suitable for editing.
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.UNINDENT
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.INDENT 0.0
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.TP
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.B \-\-build numosds layer1 ...
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will create a relatively generic map with the given layer
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structure. See below for examples.
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.UNINDENT
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.INDENT 0.0
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.TP
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.B \-\-test ...
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.TP
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.B will perform a dry run of a CRUSH mapping for a range of input object
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.TP
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.B \-\-help for more information.
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.UNINDENT
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.SH OPTIONS
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.INDENT 0.0
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.TP
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.B \-o outfile
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will specify the output file.
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.UNINDENT
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.INDENT 0.0
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.TP
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.B \-\-clobber
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will allow the tool to overwrite an existing outfile (it will normally refuse).
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.UNINDENT
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.SH BUILDING A MAP
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.sp
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The build mode will generate relatively generic hierarchical maps. The
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first argument simply specifies the number of devices (leaves) in the
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CRUSH hierarchy. Each layer describes how the layer (or raw devices)
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preceding it should be grouped.
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.sp
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Each layer consists of:
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.sp
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.nf
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.ft C
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name ( uniform | list | tree | straw ) size
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.ft P
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.fi
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.sp
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The first element is the name for the elements in the layer
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(e.g. "rack"). Each element\(aqs name will be append a number to the
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provided name.
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.sp
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The second component is the type of CRUSH bucket.
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.sp
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The third component is the maximum size of the bucket. If the size is
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0, a single bucket will be generated that includes everything in the
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preceding layer.
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.SH EXAMPLE
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.sp
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Suppose we have 128 devices, each grouped into shelves with 4 devices
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each, and 8 shelves per rack. We could create a three level hierarchy
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with:
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.sp
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.nf
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.ft C
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crushtool \-\-build 128 shelf uniform 4 rack straw 8 root straw 0 \-o map
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.ft P
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.fi
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.sp
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To adjust the default (generic) mapping rules, we can run:
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.sp
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.nf
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.ft C
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# decompile
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crushtool \-d map \-o map.txt
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# edit
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vi map.txt
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# recompile
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crushtool \-c map.txt \-o map
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.ft P
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.fi
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.SH AVAILABILITY
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.sp
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\fBcrushtool\fP is part of the Ceph distributed file system. Please
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refer to the Ceph documentation at \fI\%http://ceph.com/docs\fP for more
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information.
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.SH SEE ALSO
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.sp
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\fBceph\fP(8),
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\fBosdmaptool\fP(8),
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\fBmkcephfs\fP(8)
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.SH COPYRIGHT
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2012, Inktank Storage, Inc.
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.\" Generated by docutils manpage writer.
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