mirror of
https://github.com/ceph/ceph
synced 2024-12-22 19:34:30 +00:00
5ac52de003
Clean up the output messages; add some function documentation and some unit tests. Signed-off-by: caleb miles <caleb.miles@inktank.com>
118 lines
2.8 KiB
ReStructuredText
118 lines
2.8 KiB
ReStructuredText
==========================================
|
|
crushtool -- CRUSH map manipulation tool
|
|
==========================================
|
|
|
|
.. program:: crushtool
|
|
|
|
Synopsis
|
|
========
|
|
|
|
| **crushtool** ( -d *map* | -c *map.txt* | --build *numosds*
|
|
*layer1* *...* ) [ -o *outfile* [ --clobber ]]
|
|
|
|
|
|
Description
|
|
===========
|
|
|
|
**crushtool** is a utility that lets you create, compile, and
|
|
decompile CRUSH map files.
|
|
|
|
CRUSH is a pseudo-random data distribution algorithm that efficiently
|
|
maps input values (typically data objects) across a heterogeneous,
|
|
hierarchically structured device map. The algorithm was originally
|
|
described in detail in the following paper (although it has evolved
|
|
some since then):
|
|
|
|
http://www.ssrc.ucsc.edu/Papers/weil-sc06.pdf
|
|
|
|
The tool has four modes of operation.
|
|
|
|
.. option:: -c map.txt
|
|
|
|
will compile a plaintext map.txt into a binary map file.
|
|
|
|
.. option:: -d map
|
|
|
|
will take the compiled map and decompile it into a plaintext source
|
|
file, suitable for editing.
|
|
|
|
.. option:: --build numosds layer1 ...
|
|
|
|
will create a relatively generic map with the given layer
|
|
structure. See below for examples.
|
|
|
|
.. option:: --test ...
|
|
will perform a dry run of a CRUSH mapping for a range of input object
|
|
names, see crushtool --help for more information.
|
|
|
|
Options
|
|
=======
|
|
|
|
.. option:: -o outfile
|
|
|
|
will specify the output file.
|
|
|
|
.. option:: --clobber
|
|
|
|
will allow the tool to overwrite an existing outfile (it will normally refuse).
|
|
|
|
|
|
Building a map
|
|
==============
|
|
|
|
The build mode will generate relatively generic hierarchical maps. The
|
|
first argument simply specifies the number of devices (leaves) in the
|
|
CRUSH hierarchy. Each layer describes how the layer (or raw devices)
|
|
preceding it should be grouped.
|
|
|
|
Each layer consists of::
|
|
|
|
name ( uniform | list | tree | straw ) size
|
|
|
|
The first element is the name for the elements in the layer
|
|
(e.g. "rack"). Each element's name will be append a number to the
|
|
provided name.
|
|
|
|
The second component is the type of CRUSH bucket.
|
|
|
|
The third component is the maximum size of the bucket. If the size is
|
|
0, a single bucket will be generated that includes everything in the
|
|
preceding layer.
|
|
|
|
|
|
Example
|
|
=======
|
|
|
|
Suppose we have 128 devices, each grouped into shelves with 4 devices
|
|
each, and 8 shelves per rack. We could create a three level hierarchy
|
|
with::
|
|
|
|
crushtool --build 128 shelf uniform 4 rack straw 8 root straw 0 -o map
|
|
|
|
To adjust the default (generic) mapping rules, we can run::
|
|
|
|
# decompile
|
|
crushtool -d map -o map.txt
|
|
|
|
# edit
|
|
vi map.txt
|
|
|
|
# recompile
|
|
crushtool -c map.txt -o map
|
|
|
|
|
|
Availability
|
|
============
|
|
|
|
**crushtool** is part of the Ceph distributed file system. Please
|
|
refer to the Ceph documentation at http://ceph.com/docs for more
|
|
information.
|
|
|
|
|
|
See also
|
|
========
|
|
|
|
:doc:`ceph <ceph>`\(8),
|
|
:doc:`osdmaptool <osdmaptool>`\(8),
|
|
:doc:`mkcephfs <mkcephfs>`\(8)
|