Chapter 3. Configuring OpenStack to use Ceph block devices

Procedure

1. Edit the Cinder configuration file:

   [root@cinder ~]# vim /etc/cinder/cinder.conf

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2. In the [DEFAULT] section, enable Ceph as a backend for Cinder:

   enabled_backends = ceph

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3. Ensure that the Glance API version is set to 2. If you are configuring multiple cinder back ends in enabled_backends, the glance_api_version = 2 setting must be in the [DEFAULT] section and not the [ceph] section.

   glance_api_version = 2

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4. Create a [ceph] section in the cinder.conf file. Add the Ceph settings in the following steps under the [ceph] section.

5. Specify the volume_driver setting and set it to use the Ceph block device driver:

   volume_driver = cinder.volume.drivers.rbd.RBDDriver

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6. Specify the cluster name and Ceph configuration file location. In typical deployments the Ceph cluster has a cluster name of ceph and a Ceph configuration file at /etc/ceph/ceph.conf. If the Ceph cluster name is not ceph, specify the cluster name and configuration file path appropriately:

   rbd_cluster_name = us-west
   rbd_ceph_conf = /etc/ceph/us-west.conf

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7. By default, Red Hat OpenStack Platform stores Ceph volumes in the rbd pool. To use the volumes pool created earlier, specify the rbd_pool setting and set the volumes pool:

   rbd_pool = volumes

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8. Red Hat OpenStack Platform does not have a default user name or a UUID of the secret for volumes. Specify rbd_user and set it to the cinder user. Then, specify the rbd_secret_uuid setting and set it to the generated UUID stored in the uuid-secret.txt file:

   rbd_user = cinder
   rbd_secret_uuid = 4b5fd580-360c-4f8c-abb5-c83bb9a3f964

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9. Specify the following settings:

   rbd_flatten_volume_from_snapshot = false
   rbd_max_clone_depth = 5
   rbd_store_chunk_size = 4
   rados_connect_timeout = -1

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   When you configure Cinder to use Ceph block devices, the configuration file might look similar to this:

   Example

   [DEFAULT]
   enabled_backends = ceph
   glance_api_version = 2
   …
   
   [ceph]
   volume_driver = cinder.volume.drivers.rbd.RBDDriver
   rbd_cluster_name = ceph
   rbd_pool = volumes
   rbd_user = cinder
   rbd_ceph_conf = /etc/ceph/ceph.conf
   rbd_flatten_volume_from_snapshot = false
   rbd_secret_uuid = 4b5fd580-360c-4f8c-abb5-c83bb9a3f964
   rbd_max_clone_depth = 5
   rbd_store_chunk_size = 4
   rados_connect_timeout = -1

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   Note

   Consider removing the default [lvm] section and its settings.

Procedure

1. Edit the Cinder configuration file:

   [root@cinder ~]# vim /etc/cinder/cinder.conf

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2. Go to the [ceph] section of the configuration file.

3. Specify the backup_driver setting and set it to the Ceph driver:

   backup_driver = cinder.backup.drivers.ceph

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4. Specify the backup_ceph_conf setting and specify the path to the Ceph configuration file:

   backup_ceph_conf = /etc/ceph/ceph.conf

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   Note

   The Cinder backup Ceph configuration file may be different from the Ceph configuration file used for Cinder. For example, it can point to a different Ceph storage cluster.

5. Specify the Ceph pool for backups:

   backup_ceph_pool = backups

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   Note

   The Ceph configuration file used for Cinder backup might be different from the Ceph configuration file used for Cinder.

6. Specify the backup_ceph_user setting and specify the user as cinder-backup:

   backup_ceph_user = cinder-backup

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7. Specify the following settings:

   backup_ceph_chunk_size = 134217728
   backup_ceph_stripe_unit = 0
   backup_ceph_stripe_count = 0
   restore_discard_excess_bytes = true

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   When you include the Cinder options, the [ceph] section of the cinder.conf file might look similar to this:

   Example

   [ceph]
   volume_driver = cinder.volume.drivers.rbd.RBDDriver
   rbd_cluster_name = ceph
   rbd_pool = volumes
   rbd_user = cinder
   rbd_ceph_conf = /etc/ceph/ceph.conf
   rbd_flatten_volume_from_snapshot = false
   rbd_secret_uuid = 4b5fd580-360c-4f8c-abb5-c83bb9a3f964
   rbd_max_clone_depth = 5
   rbd_store_chunk_size = 4
   rados_connect_timeout = -1
   
   backup_driver = cinder.backup.drivers.ceph
   backup_ceph_user = cinder-backup
   backup_ceph_conf = /etc/ceph/ceph.conf
   backup_ceph_chunk_size = 134217728
   backup_ceph_pool = backups
   backup_ceph_stripe_unit = 0
   backup_ceph_stripe_count = 0
   restore_discard_excess_bytes = true

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8. Verify if Cinder backup is enabled:

   [root@cinder ~]# cat /etc/openstack-dashboard/local_settings | grep enable_backup

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   If enable_backup is set to False, then edit the local_settings file and set it to True.

   Example

   OPENSTACK_CINDER_FEATURES = {
       'enable_backup': True,
   }

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Procedure

1. To use Ceph block devices by default, edit the /etc/glance/glance-api.conf file. If you used different pool, user or Ceph configuration file settings apply the appropriate values. Uncomment the following settings if necessary and change their values accordingly:

   [root@glance ~]# vim /etc/glance/glance-api.conf

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   stores = rbd
   default_store = rbd
   rbd_store_chunk_size = 8
   rbd_store_pool = images
   rbd_store_user = glance
   rbd_store_ceph_conf = /etc/ceph/ceph.conf

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2. To enable copy-on-write (CoW) cloning set show_image_direct_url to True.

   show_image_direct_url = True

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   Important

   Enabling CoW exposes the back end location via Glance’s API, so the endpoint should not be publicly accessible.

3. Disable cache management if necessary. The flavor should be set to keystone only, not keystone+cachemanagement.

   flavor = keystone

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4. Red Hat recommends the following properties for images:

   hw_scsi_model=virtio-scsi
   hw_disk_bus=scsi
   hw_qemu_guest_agent=yes
   os_require_quiesce=yes

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   The virtio-scsi controller gets better performance and provides support for discard operations. For systems using SCSI/SAS drives, connect every Cinder block device to that controller. Also, enable the QEMU guest agent and send fs-freeze/thaw calls through the QEMU guest agent.

Procedure

1. Edit the Ceph configuration file:

   [root@nova ~]# vim /etc/ceph/ceph.conf

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2. Add the following section to the [client] section of the Ceph configuration file:

   [client]
   rbd cache = true
   rbd cache writethrough until flush = true
   rbd concurrent management ops = 20
   admin socket = /var/run/ceph/guests/$cluster-$type.$id.$pid.$cctid.asok
   log file = /var/log/ceph/qemu-guest-$pid.log

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3. Create new directories for the admin socket and log file, and change the directory permissions to use the qemu user and libvirtd group:

   [root@nova ~]# mkdir -p /var/run/ceph/guests/ /var/log/ceph/
   [root@nova ~]# chown qemu:libvirt /var/run/ceph/guests /var/log/ceph/

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   Note

   The directories must be allowed by SELinux or AppArmor.

4. On each Nova node, edit the /etc/nova/nova.conf file. Under the [libvirt] section, configure the following settings:

   Example

   [libvirt]
   images_type = rbd
   images_rbd_pool = vms
   images_rbd_ceph_conf = /etc/ceph/ceph.conf
   rbd_user = cinder
   rbd_secret_uuid = 4b5fd580-360c-4f8c-abb5-c83bb9a3f964
   disk_cachemodes="network=writeback"
   inject_password = false
   inject_key = false
   inject_partition = -2
   live_migration_flag="VIR_MIGRATE_UNDEFINE_SOURCE,VIR_MIGRATE_PEER2PEER,VIR_MIGRATE_LIVE,VIR_MIGRATE_PERSIST_DEST,VIR_MIGRATE_TUNNELLED"
   hw_disk_discard = unmap

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   Replace the UUID in rbd_user_secret with the UUID in the uuid-secret.txt file.

Procedure

1. Load the block device pool names and Ceph user names into the configuration file.

2. Restart the appropriate OpenStack services after modifying the corresponding configuration files:

   [root@osp ~]# systemctl restart openstack-cinder-volume
   [root@osp ~]# systemctl restart openstack-cinder-backup
   [root@osp ~]# systemctl restart openstack-glance-api
   [root@osp ~]# systemctl restart openstack-nova-compute

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