An optical jukebox is a robotic data storage device that can automatically load and unload optical discs, such as Compact Disc, DVD, Ultra Density Optical or Blu-ray and can provide terabytes (TB) or petabytes (PB) of tertiary storage. The devices are often called optical disk libraries, "optical storage archives", robotic drives, or autochangers. Jukebox devices may have up to 2,000 slots for disks, and usually have a picking device that traverses the slots and drives. Zerras Inc. provides a removeable capsule that holds up to 200 discs per library which can be scaled-out to manage 1600 discs per 42U rack unit. The 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. Seek times and transfer rates vary depending upon the optical technology used. History and function One of the first examples of an optical jukebox was the unit designed and built at the Royal Aerospace Establishment at Farnborough, England. The unit had twin read/write heads, 12" WORM disks and the carousels were pneumatically driven. It was produced to replace the 1/2 inch magnetic tape devices that were being used to store satellite data. Jukeboxes are used in high-capacity archive storage environments such data centers and on-premise server rooms to store long-term data such as imaging, medical, compliance records, video and other high-value data assets, objects, and files. Hierarchical storage management is a strategy that moves little-used or unused files from fast magnetic storage to optical jukebox devices in a process called migration. If the files are needed, they are migrated back to magnetic disk. Optical disc libraries are also useful for making backups and in disaster recovery situations. Today one of the most important uses for jukeboxes is to archive data. Archiving data is different from backups in that the data is stored on media designed to last up to 100 years. The data is usually permanently written on Write Once Read Many (WORM)-type discs so it cannot be erased or changed. Jukeboxes typically contain internal SCSI- or SATA-based recordable drives (CD-ROM, CD-R, DVD-ROM, DVD-R, DVD-RAM, UDO or Blu-ray) that connect directly to a file server and are managed by a third-party jukebox management software. This software controls the movement of media within the jukebox, and the pre-mastering of data prior to the recording process. Before the advent of the modern SAN and