When defining an object storage group, you can specify up to eight real optical libraries or up to eight pseudo optical libraries. You cannot mix real and pseudo libraries in a storage group definition. If the object's storage class indicates that the object should reside on optical, OAM stores the object using any optical drive associated with any of the optical libraries listed in the object storage group definition, and any eligible optical volume that is accessible by the drive selected.

The object or object backup storage groups can share optical libraries. A single optical library can contain optical volumes belonging to several object or object backup storage groups. There can be multiple object storage groups per system.