ceph/doc/start/block.rst
Tommi Virtanen 76fbdfb3dd doc: Add index entries, remove glossary as it's practically replaced by the index.
Signed-off-by: Tommi Virtanen <tommi.virtanen@dreamhost.com>
2011-09-23 15:55:00 -07:00

90 lines
2.4 KiB
ReStructuredText

.. index:: RBD
=====================
Starting to use RBD
=====================
Introduction
============
`RBD` is the block device component of Ceph. It provides a block
device interface to a Linux machine, while striping the data across
multiple `RADOS` objects for improved performance. For more
information, see :ref:`rbd`.
Installation
============
To use `RBD`, you need to install a Ceph cluster. Follow the
instructions in :doc:`/ops/install/index`. Continue with these
instructions once you have a healthy cluster running.
Setup
=====
The default `pool` used by `RBD` is called ``rbd``. It is created for
you as part of the installation. If you wish to use multiple pools,
for example for access control, see :ref:`create-new-pool`.
First, we need a ``client`` key that is authorized to access the right
pool. Follow the instructions in :ref:`add-new-key`. Let's set the
``id`` of the key to be ``bar``. You could set up one key per machine
using `RBD`, or let them share a single key; your call. Make sure the
keyring containing the new key is available on the machine.
Then, authorize the key to access the new pool. Follow the
instructions in :ref:`auth-pool`.
Usage
=====
`RBD` can be accessed in two ways:
- as a block device on a Linux machine
- via the ``rbd`` network storage driver in Qemu/KVM
.. rubric:: Example: As a block device
Using the ``client.bar`` key you set up earlier, we can create an RBD
image called ``tengigs``::
rbd --name=client.bar create --size=10240 tengigs
And then make that visible as a block device::
touch secretfile
chmod go= secretfile
ceph-authtool --name=bar --print-key /etc/ceph/client.bar.keyring >secretfile
rbd map tengigs --user bar --secret secretfile
.. todo:: the secretfile part is really clumsy
For more information, see :doc:`rbd </man/8/rbd>`\(8).
.. rubric:: Example: As a Qemu/KVM storage driver via Libvirt
You'll need ``kvm`` v0.15, and ``libvirt`` v0.8.7 or newer.
Create the RBD image as above, and then refer to it in the ``libvirt``
virtual machine configuration::
<disk type='network' device='disk'>
<source protocol='rbd' name='rbd/tengigs'>
<host name='10.0.0.101' port='6789'/>
<host name='10.0.0.102' port='6789'/>
<host name='10.0.0.103' port='6789'/>
</source>
<target dev='vda' bus='virtio'/>
</disk
.. todo:: use secret keys
.. todo:: ceph.conf usage for mon addresses
.. todo:: pending libvirt xml schema changes