A grouped volume is an optical volume that is associated with an Object storage group. Volumes are grouped to subdivide the total available optical storage. A grouped volume contains objects from a single Object storage group.

A scratch volume becomes a grouped volume when OAM uses it to satisfy a write request that specifies an Object storage group name. When a scratch volume becomes a grouped volume, both volumes on the optical disk become grouped volumes that are assigned to the same Object storage group.

Taken together, all of the optical volumes that are associated with an Object storage group constitute the optical volume portion of the hierarchy in that Object storage group.