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 previously  selected  type  that
              ceph-dencoder is able to generate.

       select_test <n>
              Select the given built-in test instance as 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  https://docs.ceph.com  for  more
       information.

SEE ALSO

       ceph(8)

COPYRIGHT

       2010-2024, Inktank  Storage,  Inc.  and  contributors.  Licensed  under  Creative  Commons
       Attribution Share Alike 3.0 (CC-BY-SA-3.0)