mirror of
https://github.com/ceph/ceph
synced 2024-12-14 15:35:45 +00:00
112 lines
3.1 KiB
ReStructuredText
112 lines
3.1 KiB
ReStructuredText
=======================
|
||
Block Device Commands
|
||
=======================
|
||
|
||
.. index:: Ceph Block Device; image management
|
||
|
||
The ``rbd`` command enables you to create, list, introspect and remove block
|
||
device images. You can also use it to clone images, create snapshots,
|
||
rollback an image to a snapshot, view a snapshot, etc. For details on using
|
||
the ``rbd`` command, see `RBD – Manage RADOS Block Device (RBD) Images`_ for
|
||
details.
|
||
|
||
.. important:: To use Ceph Block Device commands, you must have access to
|
||
a running Ceph cluster.
|
||
|
||
|
||
Creating a Block Device Image
|
||
=============================
|
||
|
||
Before you can add a block device to a node, you must create an image for it in
|
||
the :term:`Ceph Storage Cluster` first. To create a block device image, execute
|
||
the following::
|
||
|
||
rbd create {image-name} --size {megabytes} --pool {pool-name}
|
||
|
||
For example, to create a 1GB image named ``foo`` that stores information in a
|
||
pool named ``swimmingpool``, execute the following::
|
||
|
||
rbd create foo --size 1024
|
||
rbd create bar --size 1024 --pool swimmingpool
|
||
|
||
.. note:: You must create a pool first before you can specify it as a
|
||
source. See `Storage Pools`_ for details.
|
||
|
||
Listing Block Device Images
|
||
===========================
|
||
|
||
To list block devices in the ``rbd`` pool, execute the following
|
||
(i.e., ``rbd`` is the default pool name)::
|
||
|
||
rbd ls
|
||
|
||
To list block devices in a particular pool, execute the following,
|
||
but replace ``{poolname}`` with the name of the pool::
|
||
|
||
rbd ls {poolname}
|
||
|
||
For example::
|
||
|
||
rbd ls swimmingpool
|
||
|
||
Retrieving Image Information
|
||
============================
|
||
|
||
To retrieve information from a particular image, execute the following,
|
||
but replace ``{image-name}`` with the name for the image::
|
||
|
||
rbd --image {image-name} info
|
||
|
||
For example::
|
||
|
||
rbd --image foo info
|
||
|
||
To retrieve information from an image within a pool, execute the following,
|
||
but replace ``{image-name}`` with the name of the image and replace ``{pool-name}``
|
||
with the name of the pool::
|
||
|
||
rbd --image {image-name} -p {pool-name} info
|
||
|
||
For example::
|
||
|
||
rbd --image bar -p swimmingpool info
|
||
|
||
Resizing a Block Device Image
|
||
=============================
|
||
|
||
:term:`Ceph Block Device` images are thin provisioned. They don't actually use
|
||
any physical storage until you begin saving data to them. However, they do have
|
||
a maximum capacity that you set with the ``--size`` option. If you want to
|
||
increase (or decrease) the maximum size of a Ceph Block Device image, execute
|
||
the following::
|
||
|
||
rbd resize --image foo --size 2048
|
||
|
||
|
||
Removing a Block Device Image
|
||
=============================
|
||
|
||
To remove a block device, execute the following, but replace ``{image-name}``
|
||
with the name of the image you want to remove::
|
||
|
||
rbd rm {image-name}
|
||
|
||
For example::
|
||
|
||
rbd rm foo
|
||
|
||
To remove a block device from a pool, execute the following, but replace
|
||
``{image-name}`` with the name of the image to remove and replace
|
||
``{pool-name}`` with the name of the pool::
|
||
|
||
rbd rm {image-name} -p {pool-name}
|
||
|
||
For example::
|
||
|
||
rbd rm bar -p swimmingpool
|
||
|
||
|
||
|
||
.. _Storage Pools: ../../rados/operations/pools
|
||
.. _RBD – Manage RADOS Block Device (RBD) Images: ../../man/8/rbd/
|