Plasmon UDO

Utilising the latest blue-laser technology, Plasmon's UDO (ultra density optical) storage system is touted as the replacement for MO (magneto optical). It's aimed primarily at areas such as document management and medical archiving. MO has always been hampered by the need for backward compatibility with earlier generations, and has effectively reached the end of the road with few vendors showing any interest in further development. One of Plasmon's requirements was physical compatibility with MO. The drives therefore have the same dimensions, and the 30GB cartridges are exactly the same form factor so will fit comfortably in MO libraries. This is to ensure that MO and UDO drives can be mixed and matched in the same library, allowing businesses to migrate to the new format without having to purchase complete new systems. However, it's important to understand that the formats themselves aren't compatible - UDO drives can't read MO media.

Blu-ray forms the basis for the UDO specification, but with one key difference. A 405nm blue violet laser is still used but the numerical aperture (NA, equivalent to a photographer's f-number) is 0.7 as opposed to Blu-ray's 0.85. Plasmon took this decision as it felt that manufacturing processes for the lens would be more cost-effective. Consequently, as the laser spot is larger, storage capacity is lower. The protective layer, or media substrate, is the same as Blu-ray, which is 0.1mm. The second generation of UDO is expected to increase capacity to 60GB using a 0.7NA, but there's likely to be a transition to a 0.85NA for the third generation, which aims to increase capacity to 120GB. It's also worth noting that unlike PDD media, UDO media is double sided.

Installation proved to be a major headache thanks mainly to Plasmon's use of 8KB sectors. Because of this, the drive only supports Windows 2000 and XP with the KB831293 hotfix applied - this prevents systems from crashing with a STOP error! Don't try using it with Windows Server 2003 - all our tests servers threw up a blue screen as soon as a UDO disk was inserted. Even with this patch installed you'll need to load the bundled Software Architects utility, although this only allows it to function with rewritable discs. To utilise the WORM media, you must use Plasmon's Diamond software, which causes the disk to appear as a standard disk drive.

Performance under Diamond's control was below the quoted figures. Iometer returned 4.7MB/sec and 2.6MB/sec for read/write operations respectively. Real-world tests delivered similar results, as copying a single 690MB video file to and from the UDO drive returned 2.5MB/sec and 4.3MB/sec. A 623MB collection of 4,600 small files caused a few problems with read/write speeds dropping to 3.75MB/sec and 0.82MB/sec. Things perked up with Software Architects at the helm. Read/write speeds for the video file increased to 7.4MB/sec and 3.2MB/sec, while the mixture returned 3.15MB/sec and 1.22MB/sec.

At this early stage of development, it's difficult to say whether UDO or PDD is the better format. Both offer equally low storage costs and although Sony delivers a superior performance, Plasmon scores with its support for the MO form factor. This allows UDO to slot neatly into existing libraries making it a better bet for upgrading your archiving at the enterprise level.