US Patent 8042123 Optical disc handling for standard slim drive

A media library appliance comprises optical disc handling robotics developed for dual standard slim drives in a vertical orientation. The disc handling robotics comprise a disc transfer assembly for transferring discs to and from a rotatable circular carousel surrounding the optical drives. Each slim drive resides in a separate field-replaceable unit (“FRU”) that can be replaced by a customer in the field without powering down the appliance. The FRU includes various features that allow accurate 3-axis alignment and registration of the optical drive within the appliance.