mirror of
https://github.com/ceph/ceph
synced 2024-12-29 06:52:35 +00:00
0cb56e0f13
RTD does not support installing system packages, the only ways to install dependencies are setuptools and pip. while ditaa is a tool written in Java. so we need to find a native python tool allowing us to render ditaa images. plantweb is able to the web service for rendering the ditaa diagram. so let's use it as a fallback if "ditaa" is not around. also start a new line after the directive, otherwise planweb server will return 500 at seeing the diagram. Signed-off-by: Kefu Chai <kchai@redhat.com>
395 lines
15 KiB
ReStructuredText
395 lines
15 KiB
ReStructuredText
=============================
|
|
Block Devices and OpenStack
|
|
=============================
|
|
|
|
.. index:: Ceph Block Device; 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 node 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
|
|
access to a running Ceph Storage Cluster.
|
|
|
|
Three 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
|
|
Cinder services.
|
|
|
|
- **Guest Disks**: Guest disks are guest operating system disks. By default,
|
|
when you boot a virtual machine, its disk appears as a file on the file system
|
|
of the hypervisor (usually under ``/var/lib/nova/instances/<uuid>/``). Prior
|
|
to OpenStack Havana, the only way to boot a VM in Ceph was to use the
|
|
boot-from-volume functionality of Cinder. However, now it is possible to boot
|
|
every virtual machine inside Ceph directly without using Cinder, which is
|
|
advantageous because it allows you to perform maintenance operations easily
|
|
with the live-migration process. Additionally, if your hypervisor dies it is
|
|
also convenient to trigger ``nova evacuate`` and run the virtual machine
|
|
elsewhere almost seamlessly. In doing so,
|
|
:ref:`exclusive locks <rbd-exclusive-locks>` prevent multiple
|
|
compute nodes from concurrently accessing the guest disk.
|
|
|
|
|
|
You can use OpenStack Glance to store images in a Ceph Block Device, and you
|
|
can use Cinder to boot a VM using a copy-on-write clone of an image.
|
|
|
|
The instructions below detail the setup for Glance, Cinder and Nova, 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.
|
|
|
|
.. important:: Using QCOW2 for hosting a virtual machine disk is NOT recommended.
|
|
If you want to boot virtual machines in Ceph (ephemeral backend or boot
|
|
from volume), please use the ``raw`` image format within Glance.
|
|
|
|
.. index:: pools; OpenStack
|
|
|
|
Create a Pool
|
|
=============
|
|
|
|
By default, Ceph block devices use the ``rbd`` pool. You may use any available
|
|
pool. We recommend creating a pool for Cinder and a pool for Glance. Ensure
|
|
your Ceph cluster is running, then create the pools. ::
|
|
|
|
ceph osd pool create volumes
|
|
ceph osd pool create images
|
|
ceph osd pool create backups
|
|
ceph osd pool create vms
|
|
|
|
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.
|
|
|
|
Newly created pools must be initialized prior to use. Use the ``rbd`` tool
|
|
to initialize the pools::
|
|
|
|
rbd pool init volumes
|
|
rbd pool init images
|
|
rbd pool init backups
|
|
rbd pool init vms
|
|
|
|
.. _Create a Pool: ../../rados/operations/pools#createpool
|
|
.. _Placement Groups: ../../rados/operations/placement-groups
|
|
|
|
|
|
Configure OpenStack Ceph Clients
|
|
================================
|
|
|
|
The nodes running ``glance-api``, ``cinder-volume``, ``nova-compute`` and
|
|
``cinder-backup`` 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`` node, you will need the Python bindings for ``librbd``::
|
|
|
|
sudo apt-get install python-rbd
|
|
sudo yum install python-rbd
|
|
|
|
On the ``nova-compute``, ``cinder-backup`` and on the ``cinder-volume`` node,
|
|
use both the Python bindings and the client command line tools::
|
|
|
|
sudo apt-get install ceph-common
|
|
sudo yum install ceph-common
|
|
|
|
|
|
Setup Ceph Client Authentication
|
|
--------------------------------
|
|
|
|
If you have `cephx authentication`_ enabled, create a new user for Nova/Cinder
|
|
and Glance. Execute the following::
|
|
|
|
ceph auth get-or-create client.glance mon 'profile rbd' osd 'profile rbd pool=images' mgr 'profile rbd pool=images'
|
|
ceph auth get-or-create client.cinder mon 'profile rbd' osd 'profile rbd pool=volumes, profile rbd pool=vms, profile rbd-read-only pool=images' mgr 'profile rbd pool=volumes, profile rbd pool=vms'
|
|
ceph auth get-or-create client.cinder-backup mon 'profile rbd' osd 'profile rbd pool=backups' mgr 'profile rbd pool=backups'
|
|
|
|
Add the keyrings for ``client.cinder``, ``client.glance``, and
|
|
``client.cinder-backup`` to the appropriate nodes and change their ownership::
|
|
|
|
ceph auth get-or-create client.glance | ssh {your-glance-api-server} sudo tee /etc/ceph/ceph.client.glance.keyring
|
|
ssh {your-glance-api-server} sudo chown glance:glance /etc/ceph/ceph.client.glance.keyring
|
|
ceph auth get-or-create client.cinder | ssh {your-volume-server} sudo tee /etc/ceph/ceph.client.cinder.keyring
|
|
ssh {your-cinder-volume-server} sudo chown cinder:cinder /etc/ceph/ceph.client.cinder.keyring
|
|
ceph auth get-or-create client.cinder-backup | ssh {your-cinder-backup-server} sudo tee /etc/ceph/ceph.client.cinder-backup.keyring
|
|
ssh {your-cinder-backup-server} sudo chown cinder:cinder /etc/ceph/ceph.client.cinder-backup.keyring
|
|
|
|
Nodes running ``nova-compute`` need the keyring file for the ``nova-compute``
|
|
process::
|
|
|
|
ceph auth get-or-create client.cinder | ssh {your-nova-compute-server} sudo tee /etc/ceph/ceph.client.cinder.keyring
|
|
|
|
They also need to store the secret key of the ``client.cinder`` user in
|
|
``libvirt``. The libvirt process needs it to access the cluster while attaching
|
|
a block device from Cinder.
|
|
|
|
Create a temporary copy of the secret key on the nodes running
|
|
``nova-compute``::
|
|
|
|
ceph auth get-key client.cinder | ssh {your-compute-node} tee client.cinder.key
|
|
|
|
Then, on the compute nodes, add the secret key to ``libvirt`` and remove the
|
|
temporary copy of the key::
|
|
|
|
uuidgen
|
|
457eb676-33da-42ec-9a8c-9293d545c337
|
|
|
|
cat > secret.xml <<EOF
|
|
<secret ephemeral='no' private='no'>
|
|
<uuid>457eb676-33da-42ec-9a8c-9293d545c337</uuid>
|
|
<usage type='ceph'>
|
|
<name>client.cinder secret</name>
|
|
</usage>
|
|
</secret>
|
|
EOF
|
|
sudo virsh secret-define --file secret.xml
|
|
Secret 457eb676-33da-42ec-9a8c-9293d545c337 created
|
|
sudo virsh secret-set-value --secret 457eb676-33da-42ec-9a8c-9293d545c337 --base64 $(cat client.cinder.key) && rm client.cinder.key secret.xml
|
|
|
|
Save the uuid of the secret for configuring ``nova-compute`` later.
|
|
|
|
.. important:: You don't necessarily need the UUID on all the compute nodes.
|
|
However from a platform consistency perspective, it's better to keep the
|
|
same UUID.
|
|
|
|
.. _cephx authentication: ../../rados/configuration/auth-config-ref/#enabling-disabling-cephx
|
|
|
|
|
|
Configure OpenStack to use Ceph
|
|
===============================
|
|
|
|
Configuring Glance
|
|
------------------
|
|
|
|
Glance can use multiple back ends to store images. To use Ceph block devices by
|
|
default, configure Glance like the following.
|
|
|
|
|
|
Kilo and after
|
|
~~~~~~~~~~~~~~
|
|
|
|
Edit ``/etc/glance/glance-api.conf`` and add under the ``[glance_store]`` section::
|
|
|
|
[glance_store]
|
|
stores = rbd
|
|
default_store = rbd
|
|
rbd_store_pool = images
|
|
rbd_store_user = glance
|
|
rbd_store_ceph_conf = /etc/ceph/ceph.conf
|
|
rbd_store_chunk_size = 8
|
|
|
|
For more information about the configuration options available in Glance please refer to the OpenStack Configuration Reference: http://docs.openstack.org/.
|
|
|
|
Enable copy-on-write cloning of images
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
Note that this exposes the back end location via Glance's API, so the endpoint
|
|
with this option enabled should not be publicly accessible.
|
|
|
|
Any OpenStack version except Mitaka
|
|
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
|
|
|
If you want to enable copy-on-write cloning of images, also add under the ``[DEFAULT]`` section::
|
|
|
|
show_image_direct_url = True
|
|
|
|
Disable cache management (any OpenStack version)
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
Disable the Glance cache management to avoid images getting cached under ``/var/lib/glance/image-cache/``,
|
|
assuming your configuration file has ``flavor = keystone+cachemanagement``::
|
|
|
|
[paste_deploy]
|
|
flavor = keystone
|
|
|
|
Image properties
|
|
~~~~~~~~~~~~~~~~
|
|
|
|
We recommend to use the following properties for your images:
|
|
|
|
- ``hw_scsi_model=virtio-scsi``: add the virtio-scsi controller and get better performance and support for discard operation
|
|
- ``hw_disk_bus=scsi``: connect every cinder block devices to that controller
|
|
- ``hw_qemu_guest_agent=yes``: enable the QEMU guest agent
|
|
- ``os_require_quiesce=yes``: send fs-freeze/thaw calls through the QEMU guest agent
|
|
|
|
|
|
Configuring Cinder
|
|
------------------
|
|
|
|
OpenStack requires a driver to interact with Ceph block devices. You must also
|
|
specify the pool name for the block device. On your OpenStack node, edit
|
|
``/etc/cinder/cinder.conf`` by adding::
|
|
|
|
[DEFAULT]
|
|
...
|
|
enabled_backends = ceph
|
|
glance_api_version = 2
|
|
...
|
|
[ceph]
|
|
volume_driver = cinder.volume.drivers.rbd.RBDDriver
|
|
volume_backend_name = ceph
|
|
rbd_pool = volumes
|
|
rbd_ceph_conf = /etc/ceph/ceph.conf
|
|
rbd_flatten_volume_from_snapshot = false
|
|
rbd_max_clone_depth = 5
|
|
rbd_store_chunk_size = 4
|
|
rados_connect_timeout = -1
|
|
|
|
If you are using `cephx authentication`_, also configure the user and uuid of
|
|
the secret you added to ``libvirt`` as documented earlier::
|
|
|
|
[ceph]
|
|
...
|
|
rbd_user = cinder
|
|
rbd_secret_uuid = 457eb676-33da-42ec-9a8c-9293d545c337
|
|
|
|
Note that if you are configuring multiple cinder back ends,
|
|
``glance_api_version = 2`` must be in the ``[DEFAULT]`` section.
|
|
|
|
|
|
Configuring Cinder Backup
|
|
-------------------------
|
|
|
|
OpenStack Cinder Backup requires a specific daemon so don't forget to install it.
|
|
On your Cinder Backup node, edit ``/etc/cinder/cinder.conf`` and add::
|
|
|
|
backup_driver = cinder.backup.drivers.ceph
|
|
backup_ceph_conf = /etc/ceph/ceph.conf
|
|
backup_ceph_user = cinder-backup
|
|
backup_ceph_chunk_size = 134217728
|
|
backup_ceph_pool = backups
|
|
backup_ceph_stripe_unit = 0
|
|
backup_ceph_stripe_count = 0
|
|
restore_discard_excess_bytes = true
|
|
|
|
|
|
Configuring Nova to attach Ceph RBD block device
|
|
------------------------------------------------
|
|
|
|
In order to attach Cinder devices (either normal block or by issuing a boot
|
|
from volume), you must tell Nova (and libvirt) which user and UUID to refer to
|
|
when attaching the device. libvirt will refer to this user when connecting and
|
|
authenticating with the Ceph cluster. ::
|
|
|
|
[libvirt]
|
|
...
|
|
rbd_user = cinder
|
|
rbd_secret_uuid = 457eb676-33da-42ec-9a8c-9293d545c337
|
|
|
|
These two flags are also used by the Nova ephemeral backend.
|
|
|
|
|
|
Configuring Nova
|
|
----------------
|
|
|
|
In order to boot all the virtual machines directly into Ceph, you must
|
|
configure the ephemeral backend for Nova.
|
|
|
|
It is recommended to enable the RBD cache in your Ceph configuration file
|
|
(enabled by default since Giant). Moreover, enabling the admin socket
|
|
brings a lot of benefits while troubleshooting. Having one socket
|
|
per virtual machine using a Ceph block device will help investigating performance and/or wrong behaviors.
|
|
|
|
This socket can be accessed like this::
|
|
|
|
ceph daemon /var/run/ceph/ceph-client.cinder.19195.32310016.asok help
|
|
|
|
Now on every compute nodes edit your Ceph configuration file::
|
|
|
|
[client]
|
|
rbd cache = true
|
|
rbd cache writethrough until flush = true
|
|
admin socket = /var/run/ceph/guests/$cluster-$type.$id.$pid.$cctid.asok
|
|
log file = /var/log/qemu/qemu-guest-$pid.log
|
|
rbd concurrent management ops = 20
|
|
|
|
Configure the permissions of these paths::
|
|
|
|
mkdir -p /var/run/ceph/guests/ /var/log/qemu/
|
|
chown qemu:libvirtd /var/run/ceph/guests /var/log/qemu/
|
|
|
|
Note that user ``qemu`` and group ``libvirtd`` can vary depending on your system.
|
|
The provided example works for RedHat based systems.
|
|
|
|
.. tip:: If your virtual machine is already running you can simply restart it to get the socket
|
|
|
|
|
|
Restart OpenStack
|
|
=================
|
|
|
|
To activate the Ceph block device driver and load the block device pool name
|
|
into the configuration, you must restart OpenStack. Thus, for Debian based
|
|
systems execute these commands on the appropriate nodes::
|
|
|
|
sudo glance-control api restart
|
|
sudo service nova-compute restart
|
|
sudo service cinder-volume restart
|
|
sudo service cinder-backup restart
|
|
|
|
For Red Hat based systems execute::
|
|
|
|
sudo service openstack-glance-api restart
|
|
sudo service openstack-nova-compute restart
|
|
sudo service openstack-cinder-volume restart
|
|
sudo service openstack-cinder-backup restart
|
|
|
|
Once OpenStack is up and running, you should be able to create a volume
|
|
and boot from it.
|
|
|
|
|
|
Booting from a Block Device
|
|
===========================
|
|
|
|
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}
|
|
|
|
You can use `qemu-img`_ to convert from one format to another. For example::
|
|
|
|
qemu-img convert -f {source-format} -O {output-format} {source-filename} {output-filename}
|
|
qemu-img convert -f qcow2 -O raw precise-cloudimg.img precise-cloudimg.raw
|
|
|
|
When Glance and Cinder are both using Ceph block devices, the image is a
|
|
copy-on-write clone, so it can create a new volume quickly. In the OpenStack
|
|
dashboard, you can boot from that volume by performing the following steps:
|
|
|
|
#. Launch a new instance.
|
|
#. Choose the image associated to the copy-on-write clone.
|
|
#. Select 'boot from volume'.
|
|
#. Select the volume you created.
|
|
|
|
.. _qemu-img: ../qemu-rbd/#running-qemu-with-rbd
|