ceph/doc/man/8/rbd.rst

===============================================
 rbd -- manage rados block device (RBD) images
===============================================

.. program:: rbd

Synopsis
========

| **rbd** [ -c *ceph.conf* ] [ -m *monaddr* ] [ -p | --pool *pool* ] [
  --size *size* ] [ --order *bits* ] [ *command* ... ]


Description
===========

**rbd** is a utility for manipulating rados block device (RBD) images,
used by the Linux rbd driver and the rbd storage driver for Qemu/KVM.
RBD images are simple block devices that are striped over objects and
stored in a RADOS object store. The size of the objects the image is
striped over must be a power of two.


Options
=======

.. option:: -c ceph.conf, --conf ceph.conf

   Use ceph.conf configuration file instead of the default /etc/ceph/ceph.conf to
   determine monitor addresses during startup.

.. option:: -m monaddress[:port]

   Connect to specified monitor (instead of looking through ceph.conf).

.. option:: -p pool, --pool pool

   Interact with the given pool. Required by most commands.


Parameters
==========

.. option:: --format format

   Specifies which object layout to use. The default is 1.

   * format 1 - Use the original format for a new rbd image. This format is
     understood by all versions of librbd and the kernel rbd module, but
     does not support newer features like cloning.

   * format 2 - Use the second rbd format, which is supported by
     librbd (but not the kernel rbd module) at this time. This adds
     support for cloning and is more easily extensible to allow more
     features in the future.

.. option:: --size size-in-mb

   Specifies the size (in megabytes) of the new rbd image.

.. option:: --order bits

   Specifies the object size expressed as a number of bits, such that
   the object size is ``1 << order``. The default is 22 (4 MB).

.. option:: --snap snap

   Specifies the snapshot name for the specific operation.

.. option:: --id username

   Specifies the username (without the ``client.`` prefix) to use with the map command.

.. option:: --keyfile filename

   Specifies a file containing the secret to use with the map command.
   If not specified, ``client.admin`` will be used by default.

.. option:: --keyring filename

   Specifies a keyring file containing a secret for the specified user
   to use with the map command.  If not specified, the default keyring
   locations will be searched.


Commands
========

.. TODO rst "option" directive seems to require --foo style options, parsing breaks on subcommands.. the args show up as bold too

:command:`ls` [*pool-name*]
  Will list all rbd images listed in the rbd_directory object.

:command:`info` [*image-name*]
  Will dump information (such as size and order) about a specific rbd image.
  If image is a clone, information about its parent is also displayed.
  If a snapshot is specified, whether it is protected is shown as well.

:command:`create` [*image-name*]
  Will create a new rbd image. You must also specify the size via --size.

:command:`clone` [*parent-snapname*] [*image-name*]
  Will create a clone (copy-on-write child) of the parent snapshot.
  Object order will be identical to that of the parent image unless
  specified. Size will be the same as the parent snapshot.

  The parent snapshot must be protected (see `rbd snap protect`).
  This requires format 2.

:command:`flatten` [*image-name*]
  If image is a clone, copy all shared blocks from the parent snapshot and
  make the child independent of the parent, severing the link between
  parent snap and child.  The parent snapshot can be unprotected and
  deleted if it has no further dependent clones.

  This requires format 2.

:command:`children` [*image-name*]
  List the clones of the image at the given snapshot. This checks
  every pool, and outputs the resulting poolname/imagename.

  This requires format 2.

:command:`resize` [*image-name*]
  Resizes rbd image. The size parameter also needs to be specified.

:command:`rm` [*image-name*]
  Deletes an rbd image (including all data blocks). If the image has
  snapshots, this fails and nothing is deleted.

:command:`export` [*image-name*] [*dest-path*]
  Exports image to dest path.

:command:`import` [*path*] [*dest-image*]
  Creates a new image and imports its data from path.

:command:`cp` [*src-image*] [*dest-image*]
  Copies the content of a src-image into the newly created dest-image.
  dest-image will have the same size, order, and format as src-image.

:command:`mv` [*src-image*] [*dest-image*]
  Renames an image.  Note: rename across pools is not supported.

:command:`snap` ls [*image-name*]
  Dumps the list of snapshots inside a specific image.

:command:`snap` create [*image-name*]
  Creates a new snapshot. Requires the snapshot name parameter specified.

:command:`snap` rollback [*image-name*]
  Rollback image content to snapshot. This will iterate through the entire blocks
  array and update the data head content to the snapshotted version.

:command:`snap` rm [*image-name*]
  Removes the specified snapshot.

:command:`snap` purge [*image-name*]
  Removes all snapshots from an image.

:command:`snap` protect [*image-name*]
  Protect a snapshot from deletion, so that clones can be made of it
  (see `rbd clone`).  Snapshots must be protected before clones are made;
  protection implies that there exist dependent cloned children that
  refer to this snapshot.  `rbd clone` will fail on a nonprotected
  snapshot.

  This requires format 2.

:command:`snap` unprotect [*image-name*]
  Unprotect a snapshot from deletion (undo `snap protect`).  If cloned
  children remain, `snap unprotect` fails.  (Note that clones may exist
  in different pools than the parent snapshot.)

  This requires format 2.

:command:`map` [*image-name*]
  Maps the specified image to a block device via the rbd kernel module.

:command:`unmap` [*device-path*]
  Unmaps the block device that was mapped via the rbd kernel module.

:command:`showmapped`
  Show the rbd images that are mapped via the rbd kernel module.

Image name
==========

In addition to using the --pool and the --snap options, the image name can include both
the pool name and the snapshot name. The image name format is as follows::

       [pool/]image-name[@snap]

Thus an image name that contains a slash character ('/') requires specifying the pool
name explicitly.


Examples
========

To create a new rbd image that is 100 GB::

       rbd -p mypool create myimage --size 102400

or alternatively::

       rbd create mypool/myimage --size 102400

To use a non-default object size (8 MB)::

       rbd create mypool/myimage --size 102400 --order 23

To delete an rbd image (be careful!)::

       rbd rm mypool/myimage

To create a new snapshot::

       rbd snap create mypool/myimage@mysnap

To create a copy-on-write clone of a protected snapshot::

       rbd clone mypool/myimage@mysnap otherpool/cloneimage

To see which clones of a snapshot exist::

       rbd children mypool/myimage@mysnap

To delete a snapshot::

       rbd snap rm mypool/myimage@mysnap

To map an image via the kernel with cephx enabled::

       rbd map mypool/myimage --id admin --keyfile secretfile

To unmap an image::

       rbd unmap /dev/rbd0

To create an image and a clone from it::

       rbd import --format 2 image mypool/parent
       rbd snap create --snap snapname mypool/parent
       rbd snap protect mypool/parent@snap
       rbd clone mypool/parent@snap otherpool/child

To change an image from one format to another, export it and then
import it as the desired format::

       rbd export mypool/myimage@snap /tmp/img
       rbd import --format 2 /tmp/img mypool/myimage2


Availability
============

**rbd** is part of the Ceph distributed file system. Please refer to
the Ceph documentation at http://ceph.com/docs for more information.


See also
========

:doc:`ceph <ceph>`\(8),
:doc:`rados <rados>`\(8)