modprobe rbd
+Get a List of RBD Images
+------------------------
+
+To mount an RBD image, first return a list of the images. ::
+
+ rbd list
+
Map a Block Device with ``rbd``
-------------------------------
+------------------+------------------------------------------------------------+
-List Block Devices
-------------------
-To list RBD block devices with the ``rbd`` command, specify the ``list`` option. ::
+Show Mapped Block Devices
+-------------------------
- rbd list
+To show RBD images mapped to kernel block devices with the ``rbd`` command,
+specify the ``showmapped`` option. ::
+
+ sudo rbd showmapped
Images are mounted as devices sequentially starting from ``0``. To list all
devices mapped to kernel objects, execute the following::
==================
RBD Snapshotting
==================
+
One of the advanced features of RADOS block devices is that you can create
snapshots of the images to retain a history of an image's state. Ceph supports
RBD snapshots from the ``rbd`` command, from a kernel object, from a
.. important:: Generally, you should stop i/o before snapshotting an image.
If the image contains a filesystem, the filesystem should be in a
consistent state before snapshotting too.
-
Create Snapshot
---------------
-<placeholder>
-You can take snapshots of RBD images.
+To create a snapshot with ``rbd``, specify the ``snap create`` option,
+the pool name, the image name and the username. If you use ``cephx`` for
+authentication, you must also specify a key or a secret file. ::
+
+ rbd --name {user-name} --keyfile=/path/to/secret --pool {pool-name} snap create --snap {snap-name} {image-name}
+
+For example::
+
+ rbd --name client.admin --pool rbd snap create --snap foo.snapname foo
List Snapshots
--------------
-<placeholder>
+To list snapshots of an image, specify the pool name, the image name, and
+the username. If you use ``cephx`` for authentication, you must also
+specify a key or a secret file. ::
+
+ rbd --name {user-name} --keyfile=/path/to/secret --pool {pool-name} snap ls {image-name}
+
+For example::
+
+ rbd --name client.admin --pool rbd snap ls foo
Rollback Snapshot
-----------------
-<placeholder>
+
+To rollback a snapshot with ``rbd``, specify the ``snap rollback`` option,
+the pool name, the image name and the username. If you use ``cephx`` for
+authentication, you must also specify a key or a secret file. ::
+
+ rbd --name {user-name} --keyfile=/path/to/secret --pool {pool-name} snap rollback --snap {snap-name} {image-name}
+
+For example::
+
+ rbd --name client.admin --pool rbd snap rollback --snap foo.snapname foo
Delete a Snapshot
-----------------
-<placeholder>
\ No newline at end of file
+To delete a snapshot with ``rbd``, specify the ``snap rm`` option,
+the pool name, the image name and the username. If you use ``cephx`` for
+authentication, you must also specify a key or a secret file. ::
+
+ rbd --name {user-name} --keyfile=/path/to/secret --pool {pool-name} snap rm --snap {snap-name} {image-name}
+
+For example::
+
+ rbd --name client.admin --pool rbd snap rm --snap foo.snapname foo