Use OpenStack Volumes with Juju / DaaS

By default, Juju will use ephemeral storage when creating virtual machines on an OpenStack cloud. This implies that if the physical disks in the underlying hypervisor have a failure, data loss may occur. Using OpenStack’s (cinder) volume storage, which in the GARR Cloud is based on Ceph, will instead enable redundant storage in a transparent way.

To this aim the root-disk-source=volume Juju constraint can be used when deploying an application. For example:

juju deploy influxdb --constraints "root-disk-source=volume"

The volume size can be specified through the root-disk constraint. For example:

juju deploy influxdb --constraints "root-disk=100G root-disk-source=volume"

Please note that the root-disk-source constraint can be set on the whole Juju model by using the set-model-constraints juju command:

juju set-model-constraints "root-disk-source=volume"