Information about Ultra Density Optical

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Ultra Density Optical (UDO) is an optical disc format designed for high-density storage of high-definition video and data.

Overview

An Ultra Density Optical disc or UDO is a 5.25" ISO cartridge optical disc which can store up to 60 GB of data. Utilising a design based on a Magneto-optical disc, but uses Phase Change technology combined with a blue violet laser, a UDO disc can store substantially more data than a magneto-optical disc or MO, because of the shorter wavelength (405 nm) of the blue-violet laser employed. MOs use a 650 nm-wavelength red laser. Because its beam width is shorter when burning to a disc than a red-laser for MO, a blue-violet laser allows more information to be stored digitally in the same amount of space.

Current generations of UDO store up to 60 GB, and a 120 GB version of UDO is in development and is expected to arrive in 2007 and after, though up to 500 GB has been speculated as a possibility for UDO. ^[1]

History

Originally an optical disc storage medium developed as a replacement for the Magneto-optical digital storage medium, Ultra Density Optical was developed beginning June 2000 and first announced by Sony on November 1st 2000. ^[2] It was later adopted with heavy investment by Plasmon, a UK technology company with extensive experience with computer archival backup systems and solutions. ^[3]

Currently UDO is being championed by its development partners Plasmon, Hewlett Packard, Asahi Pentax (responsible for the opto-mechanical assembly design) and Mitsubishi Chemical parent company of the Verbatim media storage brand, and various computer and IT solutions companies. Mitsubishi Chemical is the second major development partner of UDO media.^[4]

Specifications

Writing technology

UDO uses a Phase Change recording process that permanently alters the molecular structure of the disc surface.

Disc format

There are three versions of UDO 30: a True WORM (Write Once Read Many), an R/W (Re-Writable), and Compliant WORM (shreddable WORM).

Rewritable

The UDO Rewritable format uses a specially formulated Phase Change recording surface that allows recorded data to be deleted and modified. In practice, UDO Rewritable media operates like a standard magnetic disc. Files can be written, erased and rewritten, dynamically reallocating disc capacity. Rewritable media is typically used in archive applications where the stability and longevity of optical media is important, but the archive records change on a relatively frequent or discretionary basis. Rewritable media is typically used in archive environments where data needs to be deleted or media capacity re-used.

True write once

The UDO True Write Once format uses a different phase change recording surface than the Rewritable media. Unlike Rewritable media, the write once recording surface cannot be erased or altered, making Write Once the most stable in terms of data integrity, because the physical record is kept authentic. This level of data integrity is not usually matched by other magnetic disc or tape technologies using normal write once emulation. Write Once has been used successfully in high data integrity environments such as banks and financial institutions with similar magneto-optical discs. Its advantages are media longevity which reduces the cost and frequency of migration, and data authenticity. Common uses of True Write Once media include medical, financial, industrial and applications that have long or indefinite record retention periods with a need for unquestioned record authenticity.

Compliant write once media

UDO Compliant Write Once media has the same operational properties as UDO True Write Once media but with one clear and important difference. Through the use of a specially designed “shred” operation, individual records written to Compliant Write Once media can be destroyed once their retention period expires.

The shred function is controlled at an application level and operates only on Compliant Write Once media. It is a fully verified process and unlike the erase pass on magnetic disks, the shred operation on Phase Change media leaves no trace of any previously written data. While it is possible to shred data on magnetic discs through the use of specialized tools that repeatedly overwrite a patterned sequence, destroying individual records on magnetic tape is not possible without totally rewriting the media. Shredding data on Compliant Write Once media is noted as the most efficient and safest way to currently destroy data using UDO.

Magneto-optical comparison

The table below summarizes the differences between conventional Magneto-Optical specifications and those of the enhanced Ultra Density Optical disc.

Disc	5.25-inch UDO Rewriteable	5.25-inch UDO Write Once	5.25-inch MO system (9.1 GB)
Disc diameter	130 mm	130 mm	130 mm
Disc thickness	2.4 mm	2.4 mm	2.4 mm
Cartridge size	Same as ISO 130 mm (135 x 153 x 11 mm)	Same as ISO 130 mm (135 x 153 x 11 mm)	ISO 130 mm (135 x 153 x 11 mm)
Number of physical tracks	96,964	96,964	49,728
Sector size	8 kB	8 kB	4 kB
Number of sectors	2,504,407	2,504,407	1,118,880
Data area	29.0-61.0 mm	29.0-61.0 mm	29.7-62.5 mm
Laser wavelength	Violet (405 nm)	Violet (405 nm)	660 nm
Objective lens (NA)	0.85	0.85	0.575
Recording layer	Phase change	Phase change	Magneto-optical
Recording format	Land & groove	Land & groove	Land & groove
Recording side	Both sides	Both sides	Both sides
Track pitch	0.33 µm	0.33 µm	0.65 µm
Minimum bit length	0.13 µm	0.13 µm	0.3 µm
Recording density	15.0 Gb/in²	15.0 Gb/in²	3.3 Gb/in²
Transfer rate	4-8 MB/s	4-8 MB/s	3-6 MB/s
Error correction	LDC	LDC	LDC
Modulation	RLL (1,7)	RLL (1,7)	RLL (1,7)

^[5]

Drive mechanism

UDO Drives Specifications Summary

• Media Load Time 5 s
• Media Unload Time 3 s
• Average Seek Time 35 ms
• Buffer Memory 32 MB
• Max Sustained Transfer Rate - Read 8 MB/s
• Max Sustained Transfer Rate - Write 4 MB/s (with verification)
• MSBF - Mean Swap Between Failure 750,000 load/unload cycles
• MTBF - Mean Time Between Failure 100,000 hours
• Interface Wide Ultra 2 LVD SCSI

UDO comes in both internal and external drive guises. External drives are also available as part a robotic autoloader. All current drives are designed for heavy duty use.

Laser and optics

UDO systems use a blue-violet laser operating at a wavelength of 405 nm, similar to the one used in Blu-ray, to read and write data. Conventional MOs use red lasers at 660 nm. ^[6]

The blue-violet laser's shorter wavelength makes it possible to store more information on a 13 cm sized UDO disc. The minimum "spot size" on which a laser can be focused is limited by diffraction, and depends on the wavelength of the light and the numerical aperture of the lens used to focus it. By decreasing the wavelength, using a higher numerical aperture (0.85, compared with 0.575 for MO), the laser beam can be focused much more tightly. This produces a smaller spot on the disc than in existing MOs, and allows more information to be physically stored in the same area. [1]

The opto-mechanism design of current Plasmon UDO drives is jointly developed with Asahi Pentax.^[7]

Performance

UDO currently offers more than three times the capacity of MO, with 33% faster file access, an 8 MB/s read transfer rate, and a lower long term cost of ownership. It is estimated it can be up to 84% per gigabyte less than magneto-optical in terms of overall media cost.

Applications

Archival storage

Currently UDO has an expected data archival life of around 50 years. Apart from the storage size, the discs (like Magneto Optical discs) are designed for durability and long term reliability. This makes it ideal for backup use in banks, hospitals, governmental and financial institutions.

Secure video

A company called Blu-Laser Cinema announced in June 2005 that it was launching a new player using the UDO format to provide a secure viewing and editing platform for film production houses. Targeted towards the high-end video editing and production community, the unit featured a smart card reader and a USB dongle with an embedded biometric fingerprint reader to allow access only to authorized users. ^[8]

Features

The core technology for UDO is essentially similar to Blu-ray and also PDD (as they were all developed by Sony) although there are a number of key differences. The main features of UDO are:

Data authenticity and integrity

UDO provides absolute data authenticity for any application where archived information must remain 100% unchanged – e.g. banks, legal institutions. UDO uses a phase change recording process that permanently alters the molecular structure of true write once media, ensuring data is integral at the most fundamental level.

Long-term data retention

Long term archival storage. The design of the UDO with a tested stable recording surface, protective coating and encasement in a cartridge is expected to give it at least 50 years storage life, minimizing the frequency of data migration and management for firms requiring large amounts of important data storage. The UDO disc design is a robust design and reduces the potential for contamination of media.

High capacity and scalability

Blue laser technology gives 30 GB UDO more than three times the capacity of previous generation MO (Magneto Optical) and DVD technologies. Being removeable, UDO cartridges, combined with the off-line media management capabilities of optical storage libraries, makes UDO a much more scalable format. Rarely used data can be removed from a library, freeing up capacity yet remaining managed and accessible.

Rapid information access

UDO has a fast 35-millisecond random access capability. An 8 KB sector size helps read/write performance across a wide range of file sizes. UDO is slightly faster as it operates at Constant Angular Velocity (CAV). During reads and writes the discs spin continuously at very high speeds. In rewritable applications, UDO has a unique direct over write capability, doubling rewrite speeds by eliminating the need for a dedicated erase pass.

Low total cost of ownership

UDO has a very low archival storage total cost of ownership compared to other forms of data storage formats. With inexpensively priced 30 GB media, the cost of a UDO library compares favorably with tape or DVD solutions (which can be less reliable than UDO or MO) and can be cheaper to run than certain hard disk-based systems. UDO's ISO standard 5.25 inch media cartridge allows the use of MO and UDO media in the same library, eliminating the need for migration from 9.1 GB MO media. Planned introductions of backward-compatible 60 GB and 120 GB UDO drives make UDO a worthwhile contender for vast amounts of secure storage at a price.

References

External links

• Optical Storage Technology Association
• Plasmon