Volume placement

Storage Availability zones

When an application has been made cloud-aware and it can tolerate the loss of any of the attached volumes, availability can be further improved by using volumes from different storage zones in the data centre.

An storage availability zone is a way in which the user can specify a particular “location” in which a volume will be located. The most common usage for availability zones is to group together volumes in terms of availability but other features could be external network connectivity or redundant power. When a volume creation command is issued, an storage availability zone can be provided to specify which zone to allocate the volume.

The existing availability zones for volumes can be found running:

$ openstack availability zone list --volume
+---------------+-------------+
| Zone Name     | Zone Status |
+---------------+-------------+
| ceph-geneva-1 | available   |
| ceph-geneva-2 | available   |
| ceph-geneva-3 | available   |
+---------------+-------------+

Each of these zones have different local network switch and power inputs. Thus a failure in an individual hardware component of the ceph-geneva-a (such as a server, a network swich, a power distribution unit in a rack, ...) should not affect volumes running in other zones.

To create a volume in a particular availability zone, this should be specified at volume creation time:

$ openstack volume create --availability-zone ceph-geneva-1 ...

Note: storage availability zones are only supported for standard and io1 volume types.