NAME

       ceph-dencoder - ceph encoder/decoder utility

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

       version
              Print the version string for the ceph-dencoder binary.

       import <file>
              Read a binary blob of encoded data from the given file.  It will be placed in an in-memory buffer.

       export <file>
              Write the contents of the current in-memory buffer to the given file.

       list_types
              List the data types known to this build of ceph-dencoder.

       type <name>
              Select the given type for future encode or decode operations.

       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.

       decode Decode  the contents of the in-memory buffer into an instance of the previously selected type.  If
              there is an error, report it.

       encode Encode the contents of the in-memory instance of the previously selected  type  to  the  in-memory
              buffer.

       dump_json
              Print a JSON-formatted description of the in-memory object.

       count_tests
              Print  the  number of built-in test instances of the previosly selected type that ceph-dencoder is
              able to generate.

       select_test <n>
              Select the given build-in test instance as a the in-memory instance of the type.

       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.

       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 http://ceph.com/docs for more information.

SEE ALSO

       ceph(8)

COPYRIGHT

       2010-2023,  Inktank  Storage,  Inc.  and  contributors. Licensed under Creative Commons Attribution Share
       Alike 3.0 (CC-BY-SA-3.0)