Definition: UDO

(Ultra Density Optical) An optical disc technology developed by Plasmon and later acquired by Alliance Storage Technologies. UDO is used for long-term data archiving with a lifespan of at least 50 years. Available in both rewritable and write-once (WORM) 5.25" media, UDO debuted in 2003 with a 30GB capacity. Storage doubled to 60GB in 2007.

Although similar to rewritable CD/DVD drives used by consumers, UDO was designed with more robust engineering. For example, rewritable UDO uses eight layers in the disc compared to the typical four in consumer media.

UDO Replaced Magneto-Optic
Designed to supersede magneto-optic (MO) disks, UDO's first 30GB drives offered a big storage jump over 9.1GB, the final MO format. See blue laser, phase change disk, PDD and magneto-optic disk.

UDO Cartridges and Libraries

Plasmon libraries hold hundreds of cartridges. This robotic mechanism grabs the cartridge and inserts it into one of six drives for reading and writing.

UDO Bits

UDO uses blue laser optics and phase change recording. The bit polarity is either amorphous or crystalline, the latter appearing as a mix of white and black due to how different crystal alignments interacted with the laser beam. See phase change disc. (Image courtesy of Alliance Storage Technologies.)