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|
:orphan:
==============================================
ceph-dencoder -- ceph encoder/decoder utility
==============================================
.. program:: ceph-dencoder
Synopsis
========
| **ceph-dencoder** [commands...]
Description
===========
**ceph-dencoder** is a utility to encode, decode, and dump ceph data
structures. It is used for debugging and for testing inter-version
compatibility.
**ceph-dencoder** takes a simple list of commands and performs them
in order.
Commands
========
.. option:: version
Print the version string for the **ceph-dencoder** binary.
.. option:: import <file>
Read a binary blob of encoded data from the given file. It will be
placed in an in-memory buffer.
.. option:: export <file>
Write the contents of the current in-memory buffer to the given
file.
.. option:: list_types
List the data types known to this build of **ceph-dencoder**.
.. option:: type <name>
Select the given type for future ``encode`` or ``decode`` operations.
.. option:: 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.
.. option:: decode
Decode the contents of the in-memory buffer into an instance of the
previously selected type. If there is an error, report it.
.. option:: encode
Encode the contents of the in-memory instance of the previously
selected type to the in-memory buffer.
.. option:: dump_json
Print a JSON-formatted description of the in-memory object.
.. option:: count_tests
Print the number of built-in test instances of the previously
selected type that **ceph-dencoder** is able to generate.
.. option:: select_test <n>
Select the given built-in test instance as the in-memory instance
of the type.
.. option:: get_features
Print the decimal value of the feature set supported by this version
of **ceph-dencoder**. Each bit represents a feature. These correspond to
CEPH_FEATURE_* defines in src/include/ceph_features.h.
.. option:: set_features <f>
Set the feature bits provided to ``encode`` to *f*. This allows
you to encode objects such that they can be understood by old
versions of the software (for those types that support it).
Example
=======
Say you want to examine an attribute on an object stored by ``ceph-osd``. You can do this:
::
$ 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": "9'1",
"prior_version": "0'0",
"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": {}}
Alternatively, perhaps you wish to dump an internal CephFS metadata object, you might
do that like this:
::
$ 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": []}}
Availability
============
**ceph-dencoder** is part of Ceph, a massively scalable, open-source, distributed storage system. Please
refer to the Ceph documentation at https://docs.ceph.com for more
information.
See also
========
:doc:`ceph <ceph>`\(8)
|
