2011-09-22 17:53:34 +00:00
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.. index:: RBD
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2011-09-21 20:43:32 +00:00
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=====================
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Starting to use RBD
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=====================
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2011-09-21 21:55:11 +00:00
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Introduction
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============
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`RBD` is the block device component of Ceph. It provides a block
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device interface to a Linux machine, while striping the data across
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multiple `RADOS` objects for improved performance. For more
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information, see :ref:`rbd`.
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Installation
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============
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To use `RBD`, you need to install a Ceph cluster. Follow the
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instructions in :doc:`/ops/install/index`. Continue with these
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instructions once you have a healthy cluster running.
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Setup
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=====
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The default `pool` used by `RBD` is called ``rbd``. It is created for
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you as part of the installation. If you wish to use multiple pools,
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for example for access control, see :ref:`create-new-pool`.
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First, we need a ``client`` key that is authorized to access the right
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pool. Follow the instructions in :ref:`add-new-key`. Let's set the
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``id`` of the key to be ``bar``. You could set up one key per machine
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using `RBD`, or let them share a single key; your call. Make sure the
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keyring containing the new key is available on the machine.
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Then, authorize the key to access the new pool. Follow the
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instructions in :ref:`auth-pool`.
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Usage
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=====
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`RBD` can be accessed in two ways:
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- as a block device on a Linux machine
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- via the ``rbd`` network storage driver in Qemu/KVM
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.. rubric:: Example: As a block device
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Using the ``client.bar`` key you set up earlier, we can create an RBD
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image called ``tengigs``::
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rbd --name=client.bar create --size=10240 tengigs
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And then make that visible as a block device::
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touch secretfile
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chmod go= secretfile
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2011-09-22 22:16:56 +00:00
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ceph-authtool --name=bar --print-key /etc/ceph/client.bar.keyring >secretfile
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2011-09-21 21:55:11 +00:00
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rbd map tengigs --user bar --secret secretfile
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.. todo:: the secretfile part is really clumsy
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For more information, see :doc:`rbd </man/8/rbd>`\(8).
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.. rubric:: Example: As a Qemu/KVM storage driver via Libvirt
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You'll need ``kvm`` v0.15, and ``libvirt`` v0.8.7 or newer.
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Create the RBD image as above, and then refer to it in the ``libvirt``
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virtual machine configuration::
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<disk type='network' device='disk'>
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<source protocol='rbd' name='rbd/tengigs'>
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<host name='10.0.0.101' port='6789'/>
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<host name='10.0.0.102' port='6789'/>
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<host name='10.0.0.103' port='6789'/>
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</source>
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<target dev='vda' bus='virtio'/>
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</disk
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.. todo:: use secret keys
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.. todo:: ceph.conf usage for mon addresses
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.. todo:: pending libvirt xml schema changes
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