Understanding Storage

What stays and what goes away

The root disk and ephemeral disk of an instance are ephemeral, when you shut down they go away anything you want to save needs to be written to either a persistent volume or to network Storage.

Persistent volumes, as currently implemented, are volumes on Ceph RBD storage (though they appear as local storage when attached to VMs). While highly redundant, this storage is not backed up.. These volumes can only be connected to one instance at a time, they are not shared storage. So if you need to share files among instances or have larger data needs TIG hosted NFS Storage which is backed up and support concurrent access from multiple clients is the better choice.

Volume types

ALWAYS USE production VOLUME TYPE. This is the default so you can also just skip specifying anything at all.

The production volume type is now backed by Ceph RBD storage as mentioned above.

Occasionally we may also have an experimental volume type, don’t use this one either except on advice from TIG. this is generally for experiments and may involve wiping all experimental volumes without notice.

A note on snapshots

OpenStack allows you to snapshot your volumes, but no automated snapshots are taken. If you are about to make a potentially disruptive change it’s probably a good idea to take a snapshot. If you want periodic snapshots that’s also possible but you will need to script it yourself. Snapshots are copy on write so they don’t consume any space until changes are made to the base volume. If you need backed up storage please look at TIG hosted network Storage options.