An optical jukebox is a robotic data storage device that can automatically load and unload optical discs from drives, such as CD, DVD, Blu-ray, or UDO to provide terabytes (TB) or petabytes (PB) of tertiary storage. Such systems are also called optical disk libraries, optical storage archives, robotic drives, disc changers, or autochangers. Jukeboxes can fit hundreds of discs in a desktop or 5U carousel box or thousands in a full-rack cabinet, and usually have a picking device that traverses the slots and drives. Arrangement of the slots and picking devices affects performance and maintenance costs, depending on the robotics design, the space between a disk and the picking device, and number of drives. Seek times and transfer rates vary depending upon the drive used.