mirror of
https://github.com/ceph/ceph
synced 2024-12-27 14:03:25 +00:00
236 lines
9.0 KiB
ReStructuredText
236 lines
9.0 KiB
ReStructuredText
=============================
|
|
Block Devices and OpenStack
|
|
=============================
|
|
|
|
You may use Ceph block device images with OpenStack through ``libvirt``, which
|
|
configures the QEMU interface to ``librbd``. Ceph stripes block device images as
|
|
objects across the cluster, which means that large Ceph block device images have
|
|
better performance than a standalone server!
|
|
|
|
To use Ceph block devices with OpenStack, you must install QEMU, ``libvirt``,
|
|
and OpenStack first. We recommend using a separate physical host for your
|
|
OpenStack installation. OpenStack recommends a minimum of 8GB of RAM and a
|
|
quad-core processor. The following diagram depicts the OpenStack/Ceph
|
|
technology stack.
|
|
|
|
|
|
.. ditaa:: +---------------------------------------------------+
|
|
| OpenStack |
|
|
+---------------------------------------------------+
|
|
| libvirt |
|
|
+------------------------+--------------------------+
|
|
|
|
|
| configures
|
|
v
|
|
+---------------------------------------------------+
|
|
| QEMU |
|
|
+---------------------------------------------------+
|
|
| librbd |
|
|
+---------------------------------------------------+
|
|
| librados |
|
|
+------------------------+-+------------------------+
|
|
| OSDs | | Monitors |
|
|
+------------------------+ +------------------------+
|
|
|
|
.. important:: To use Ceph block devices with OpenStack, you must have a
|
|
running Ceph cluster.
|
|
|
|
Two parts of OpenStack integrate with Ceph's block devices:
|
|
|
|
- **Images**: OpenStack Glance manages images for VMs. Images
|
|
are immutable. OpenStack treats images as binary blobs and
|
|
downloads them accordingly.
|
|
|
|
- **Volumes**: Volumes are block devices. OpenStack uses volumes
|
|
to boot VMs, or to attach volumes to running VMs. OpenStack
|
|
manages volumes using ``nova-volume`` prior to the Folsom
|
|
release. OpenStack manages volumes using Cinder services
|
|
beginning with the Folsom release.
|
|
|
|
Beginning with OpenStack Folsom and Ceph 0.52, you can use OpenStack Glance to
|
|
store images in a Ceph block device, and you can use Cinder or ``nova-volume``
|
|
to boot a VM using a copy-on-write clone of an image.
|
|
|
|
The instructions below detail the setup for Glance and Nova/Cinder, although
|
|
they do not have to be used together. You may store images in Ceph block devices
|
|
while running VMs using a local disk, or vice versa.
|
|
|
|
Create a Pool
|
|
=============
|
|
|
|
By default, Ceph block devices use the ``rbd`` pool. You may use any available
|
|
pool. We recommend creating a pool for Nova/Cinder and a pool for Glance. Ensure
|
|
your Ceph cluster is running, then create the pools. ::
|
|
|
|
ceph osd pool create volumes 128
|
|
ceph osd pool create images 128
|
|
|
|
See `Create a Pool`_ for detail on specifying the number of placement groups for
|
|
your pools, and `Placement Groups`_ for details on the number of placement
|
|
groups you should set for your pools.
|
|
|
|
.. _Create a Pool: ../../rados/operations/pools#createpool
|
|
.. _Placement Groups: ../../rados/operations/placement-groups
|
|
|
|
|
|
Configure OpenStack Ceph Clients
|
|
================================
|
|
|
|
The hosts running ``glance-api``, ``nova-compute``, and ``nova-volume`` or
|
|
``cinder-volume`` act as Ceph clients. Each requires the ``ceph.conf`` file::
|
|
|
|
ssh {your-openstack-server} sudo tee /etc/ceph/ceph.conf </etc/ceph/ceph.conf
|
|
|
|
Install Ceph client packages
|
|
----------------------------
|
|
|
|
On the ``glance-api`` host, you'll need the Python bindings for ``librbd``::
|
|
|
|
sudo apt-get install python-ceph
|
|
|
|
On the ``nova-volume`` or ``cinder-volume`` host, use the client command line
|
|
tools::
|
|
|
|
sudo apt-get install ceph-common
|
|
|
|
|
|
Setup Ceph Client Authentication
|
|
--------------------------------
|
|
|
|
If you have `cephx authentication`_ enabled, create a new user for Nova/Cinder
|
|
and Glance.
|
|
|
|
For Ceph version 0.53 or lower, execute the following::
|
|
|
|
ceph auth get-or-create client.volumes mon 'allow r' osd 'allow x, allow rwx pool=volumes, allow rx pool=images'
|
|
ceph auth get-or-create client.images mon 'allow r' osd 'allow x, allow rwx pool=images'
|
|
|
|
In Ceph version 0.54, more specific permissions were added, so the users can be
|
|
restricted further. For Ceph version 0.54 or later, execute the following::
|
|
|
|
ceph auth get-or-create client.volumes mon 'allow r' osd 'allow class-read object_prefix rbd_children, allow rwx pool=volumes, allow rx pool=images'
|
|
ceph auth get-or-create client.images mon 'allow r' osd 'allow class-read object_prefix rbd_children, allow rwx pool=images'
|
|
|
|
Add the keyrings for ``client.volumes`` and ``client.images`` to the appropriate
|
|
hosts and change their ownership::
|
|
|
|
ceph auth get-or-create client.images | ssh {your-glance-api-server} sudo tee /etc/ceph/ceph.client.images.keyring
|
|
ssh {your-glance-api-server} sudo chown glance:glance /etc/ceph/ceph.client.images.keyring
|
|
ceph auth get-or-create client.volumes | ssh {your-volume-server} sudo tee /etc/ceph/ceph.client.volumes.keyring
|
|
ssh {your-volume-server} sudo chown cinder:cinder /etc/ceph/ceph.client.volumes.keyring
|
|
|
|
Hosts running ``nova-compute`` do not need the keyring. Instead, they
|
|
store the secret key in libvirt. Create a temporary copy of the secret
|
|
key on the hosts running ``nova-compute``::
|
|
|
|
ssh {your-compute-host} client.volumes.key <`ceph auth get-key client.volumes`
|
|
|
|
Then, on the compute hosts, add the secret key to libvirt and remove the
|
|
temporary copy of the key::
|
|
|
|
cat > secret.xml <<EOF
|
|
<secret ephemeral='no' private='no'>
|
|
<usage type='ceph'>
|
|
<name>client.volumes secret</name>
|
|
</usage>
|
|
</secret>
|
|
EOF
|
|
sudo virsh secret-define --file secret.xml
|
|
<uuid of secret is output here>
|
|
sudo virsh secret-set-value --secret {uuid of secret} --base64 $(cat client.volumes.key) && rm client.volumes.key secret.xml
|
|
|
|
Save the uuid of the secret for configuring ``nova-compute`` later.
|
|
|
|
.. _cephx authentication: ../../rados/operations/authentication
|
|
|
|
|
|
Configure OpenStack to use Ceph
|
|
===============================
|
|
|
|
Configuring Glance
|
|
------------------
|
|
|
|
Glance can use multiple back ends to store images. To use Ceph block devices by
|
|
default, edit ``/etc/glance/glance-api.conf`` and add::
|
|
|
|
default_store=rbd
|
|
rbd_store_user=images
|
|
rbd_store_pool=images
|
|
|
|
If you're using Folsom and want to enable copy-on-write cloning of
|
|
images into volumes, also add::
|
|
|
|
show_image_direct_url=True
|
|
|
|
Note that this exposes the back end location via Glance's API, so the
|
|
endpoint with this option enabled should not be publicly accessible.
|
|
|
|
|
|
Configuring Cinder/nova-volume
|
|
------------------------------
|
|
|
|
OpenStack requires a driver to interact with Ceph block devices. You must also
|
|
specify the pool name for the block device. On your OpenStack host,
|
|
edit ``/etc/cinder/cinder.conf`` and add::
|
|
|
|
volume_driver=cinder.volume.driver.RBDDriver
|
|
rbd_pool=volumes
|
|
|
|
If you're not using Cinder, replace Cinder with Nova in the previous section.
|
|
|
|
If you're using `cephx authentication`_, also configure the user and
|
|
uuid of the secret you added to libvirt earlier::
|
|
|
|
rbd_user=volumes
|
|
rbd_secret_uuid={uuid of secret}
|
|
|
|
Finally, on each host running ``cinder-volume`` or ``nova-volume``, add
|
|
``CEPH_ARGS="--id volumes"`` to the init/upstart script that starts it.
|
|
|
|
For example, on Ubuntu, add ``env CEPH_ARGS="--id volumes"``
|
|
to the top of ``/etc/init/cinder-volume.conf``.
|
|
|
|
|
|
Restart OpenStack
|
|
=================
|
|
|
|
To activate the Ceph block device driver and load the block device pool name
|
|
into the configuration, you must restart OpenStack. Navigate the directory where
|
|
you installed OpenStack, and execute the following::
|
|
|
|
./rejoin-stack.sh
|
|
|
|
If you have OpenStack configured as a service, you can also execute
|
|
these commands on the appropriate hosts::
|
|
|
|
sudo service glance-api restart
|
|
sudo service nova-compute restart
|
|
sudo service cinder-volume restart
|
|
|
|
Once OpenStack is up and running, you should be able to create a volume with
|
|
OpenStack on a Ceph block device.
|
|
|
|
|
|
Booting from a Block Device
|
|
===========================
|
|
|
|
If you're using OpenStack Folsom or later, you can create a volume from an image
|
|
using the Cinder command line tool::
|
|
|
|
cinder create --image-id {id of image} --display-name {name of volume} {size of volume}
|
|
|
|
Note that image must be raw format. You can use `qemu-img`_ to convert
|
|
from one format to another, i.e.::
|
|
|
|
qemu-img convert -f qcow2 -O raw precise-cloudimg.img precise-cloudimg.raw
|
|
|
|
Before Ceph 0.52 the image will be a full copy of the data. With Ceph 0.52 and
|
|
later when Glance and Cinder are both using Ceph block devices, the image is a
|
|
copy-on-write clone, so volume creation is very fast.
|
|
|
|
In the OpenStack dashboard you can then boot from that volume by launching a new
|
|
instance, choosing the image that you created the volume from, and selecting
|
|
'boot from volume' and the volume you created.
|
|
|
|
.. _qemu-img: ../qemu-rbd/#running-qemu-with-rbd
|