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.TH "CEPH-DENCODER" "8" "Aug 28, 2019" "dev" "Ceph"
.SH NAME
ceph-dencoder \- ceph encoder/decoder utility
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.SH SYNOPSIS
.nf
\fBceph\-dencoder\fP [commands...]
.fi
.sp
.SH DESCRIPTION
.sp
\fBceph\-dencoder\fP is a utility to encode, decode, and dump ceph data
structures.  It is used for debugging and for testing inter\-version
compatibility.
.sp
\fBceph\-dencoder\fP takes a simple list of commands and performs them
in order.
.SH COMMANDS
.INDENT 0.0
.TP
.B version
Print the version string for the \fBceph\-dencoder\fP binary.
.UNINDENT
.INDENT 0.0
.TP
.B import <file>
Read a binary blob of encoded data from the given file.  It will be
placed in an in\-memory buffer.
.UNINDENT
.INDENT 0.0
.TP
.B export <file>
Write the contents of the current in\-memory buffer to the given
file.
.UNINDENT
.INDENT 0.0
.TP
.B list_types
List the data types known to this build of \fBceph\-dencoder\fP\&.
.UNINDENT
.INDENT 0.0
.TP
.B type <name>
Select the given type for future \fBencode\fP or \fBdecode\fP operations.
.UNINDENT
.INDENT 0.0
.TP
.B skip <bytes>
Seek <bytes> into the imported file before reading data structure, use
this with objects that have a preamble/header before the object of interest.
.UNINDENT
.INDENT 0.0
.TP
.B decode
Decode the contents of the in\-memory buffer into an instance of the
previously selected type.  If there is an error, report it.
.UNINDENT
.INDENT 0.0
.TP
.B encode
Encode the contents of the in\-memory instance of the previously
selected type to the in\-memory buffer.
.UNINDENT
.INDENT 0.0
.TP
.B dump_json
Print a JSON\-formatted description of the in\-memory object.
.UNINDENT
.INDENT 0.0
.TP
.B count_tests
Print the number of built\-in test instances of the previosly
selected type that \fBceph\-dencoder\fP is able to generate.
.UNINDENT
.INDENT 0.0
.TP
.B select_test <n>
Select the given build\-in test instance as a the in\-memory instance
of the type.
.UNINDENT
.INDENT 0.0
.TP
.B get_features
Print the decimal value of the feature set supported by this version
of \fBceph\-dencoder\fP\&.  Each bit represents a feature.  These correspond to
CEPH_FEATURE_* defines in src/include/ceph_features.h.
.UNINDENT
.INDENT 0.0
.TP
.B set_features <f>
Set the feature bits provided to \fBencode\fP to \fIf\fP\&.  This allows
you to encode objects such that they can be understood by old
versions of the software (for those types that support it).
.UNINDENT
.SH EXAMPLE
.sp
Say you want to examine an attribute on an object stored by \fBceph\-osd\fP\&.  You can do this:
.INDENT 0.0
.INDENT 3.5
.sp
.nf
.ft C
$ cd /mnt/osd.12/current/2.b_head
$ attr \-l foo_bar_head_EFE6384B
Attribute "ceph.snapset" has a 31 byte value for foo_bar_head_EFE6384B
Attribute "ceph._" has a 195 byte value for foo_bar_head_EFE6384B
$ attr foo_bar_head_EFE6384B \-g ceph._ \-q > /tmp/a
$ ceph\-dencoder type object_info_t import /tmp/a decode dump_json
{ "oid": { "oid": "foo",
      "key": "bar",
      "snapid": \-2,
      "hash": 4024842315,
      "max": 0},
  "locator": { "pool": 2,
      "preferred": \-1,
      "key": "bar"},
  "category": "",
  "version": "9\(aq1",
  "prior_version": "0\(aq0",
  "last_reqid": "client.4116.0:1",
  "size": 1681,
  "mtime": "2012\-02\-21 08:58:23.666639",
  "lost": 0,
  "wrlock_by": "unknown.0.0:0",
  "snaps": [],
  "truncate_seq": 0,
  "truncate_size": 0,
  "watchers": {}}
.ft P
.fi
.UNINDENT
.UNINDENT
.sp
Alternatively, perhaps you wish to dump an internal CephFS metadata object, you might
do that like this:
.INDENT 0.0
.INDENT 3.5
.sp
.nf
.ft C
$ rados \-p metadata get mds_snaptable mds_snaptable.bin
$ ceph\-dencoder type SnapServer skip 8 import mds_snaptable.bin decode dump_json
{ "snapserver": { "last_snap": 1,
   "pending_noop": [],
   "snaps": [],
   "need_to_purge": {},
   "pending_create": [],
   "pending_destroy": []}}
.ft P
.fi
.UNINDENT
.UNINDENT
.SH AVAILABILITY
.sp
\fBceph\-dencoder\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)
.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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