1CEPH-DENCODER(8)                     Ceph                     CEPH-DENCODER(8)
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NAME

6       ceph-dencoder - ceph encoder/decoder utility
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SYNOPSIS

9       ceph-dencoder [commands...]
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11

DESCRIPTION

13       ceph-dencoder is a utility to encode, decode, and dump ceph data struc‐
14       tures.  It is used for debugging and for testing inter-version compati‐
15       bility.
16
17       ceph-dencoder  takes a simple list of commands and performs them in or‐
18       der.
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COMMANDS

21       version
22              Print the version string for the ceph-dencoder binary.
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24       import <file>
25              Read a binary blob of encoded data from the given file.  It will
26              be placed in an in-memory buffer.
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28       export <file>
29              Write  the contents of the current in-memory buffer to the given
30              file.
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32       list_types
33              List the data types known to this build of ceph-dencoder.
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35       type <name>
36              Select the given type for future encode or decode operations.
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38       skip <bytes>
39              Seek <bytes> into the imported file before reading  data  struc‐
40              ture,  use  this with objects that have a preamble/header before
41              the object of interest.
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43       decode Decode the contents of the in-memory buffer into an instance  of
44              the previously selected type.  If there is an error, report it.
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46       encode Encode  the contents of the in-memory instance of the previously
47              selected type to the in-memory buffer.
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49       dump_json
50              Print a JSON-formatted description of the in-memory object.
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52       count_tests
53              Print the number of built-in test instances  of  the  previously
54              selected type that ceph-dencoder is able to generate.
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56       select_test <n>
57              Select  the  given build-in test instance as a the in-memory in‐
58              stance of the type.
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60       get_features
61              Print the decimal value of the feature  set  supported  by  this
62              version of ceph-dencoder.  Each bit represents a feature.  These
63              correspond to CEPH_FEATURE_*  defines  in  src/include/ceph_fea‐
64              tures.h.
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66       set_features <f>
67              Set  the  feature bits provided to encode to f.  This allows you
68              to encode objects such that they can be understood by  old  ver‐
69              sions of the software (for those types that support it).
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EXAMPLE

72       Say  you  want to examine an attribute on an object stored by ceph-osd.
73       You can do this:
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75          $ cd /mnt/osd.12/current/2.b_head
76          $ attr -l foo_bar_head_EFE6384B
77          Attribute "ceph.snapset" has a 31 byte value for foo_bar_head_EFE6384B
78          Attribute "ceph._" has a 195 byte value for foo_bar_head_EFE6384B
79          $ attr foo_bar_head_EFE6384B -g ceph._ -q > /tmp/a
80          $ ceph-dencoder type object_info_t import /tmp/a decode dump_json
81          { "oid": { "oid": "foo",
82                "key": "bar",
83                "snapid": -2,
84                "hash": 4024842315,
85                "max": 0},
86            "locator": { "pool": 2,
87                "preferred": -1,
88                "key": "bar"},
89            "category": "",
90            "version": "9'1",
91            "prior_version": "0'0",
92            "last_reqid": "client.4116.0:1",
93            "size": 1681,
94            "mtime": "2012-02-21 08:58:23.666639",
95            "lost": 0,
96            "wrlock_by": "unknown.0.0:0",
97            "snaps": [],
98            "truncate_seq": 0,
99            "truncate_size": 0,
100            "watchers": {}}
101
102       Alternatively, perhaps you wish to dump an internal CephFS metadata ob‐
103       ject, you might do that like this:
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105          $ rados -p metadata get mds_snaptable mds_snaptable.bin
106          $ ceph-dencoder type SnapServer skip 8 import mds_snaptable.bin decode dump_json
107          { "snapserver": { "last_snap": 1,
108             "pending_noop": [],
109             "snaps": [],
110             "need_to_purge": {},
111             "pending_create": [],
112             "pending_destroy": []}}
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AVAILABILITY

115       ceph-dencoder  is part of Ceph, a massively scalable, open-source, dis‐
116       tributed storage system. Please refer  to  the  Ceph  documentation  at
117       http://ceph.com/docs for more information.
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SEE ALSO

120       ceph(8)
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123       2010-2022,  Inktank Storage, Inc. and contributors. Licensed under Cre‐
124       ative Commons Attribution Share Alike 3.0 (CC-BY-SA-3.0)
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129dev                              Jun 22, 2022                 CEPH-DENCODER(8)
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