Product Reviews

Although PC Pro first discussed the potential of the blue laser as far back as 1996, it's taken a full eight years for this technology to come to fruition. Like Plasmon, Sony has moved quickly into this new territory but it's targeting general storage applications such as backup along with data archiving.

Sony was originally a co-developer of the UDO format along with Plasmon and HP but dropped out to concentrate on its own Professional Disc for DATA (PDD) format. Despite Sony's protestations, the PDD specification bears more than a passing resemblance to Blu-ray, although it isn't compatible with it. The PDD lens shares the 0.85NA (numerical aperture) and it also uses the same blue-violet laser with a 405nm wavelength. The resultant narrower laser spot improves recording density, so the PDD format stores 23GB on a single-sided disc. However, the reduced depth of field requires the lens to be moved closer to the media surface and the protective substrate to be reduced to only 0.1mm; this allows the laser to focus on the recording surface underneath. The advantage of this is an improved tolerance to discs tilting or bending, which increases reliability. The drawback is that the protective layer is so thin it can no longer be subjected to the same treatment meted out to CD and DVD media. Consequently, the discs are

PDD improves performance over the 4.5MB/sec of Blu-ray to 11MB/sec and 9MB/sec for read/write operations. Sony has achieved this by using higher quality media and improved electronics including the DSP. Another difference to UDO is that PDD uses a combination of CAV (constant angular velocity) and CLV (constant linear velocity) and the drive's firmware can automatically select the most appropriate mode for the best overall performance. DIP switches at the rear can also be used to manually select a mode. One big differentiator over UDO is the disk's logical sector size of 2KB, which means the PDD drive is supported by all Windows platforms and doesn't require a hotfix to avoid system crashes.

And so to the PDD drive itself, which in typical Sony tradition is very well designed and built. The casing, even down to the mounting screw holes, is completely dust-proof and the loading bay has a dual shutter mechanism for further protection. We installed the drive on a Windows Server 2003 system, which happily accepted and identified it as a removable drive. Performance was noticeably better than UDO with Iometer reporting 10.4MB/sec and 4.3MB/sec for sequential read/write operations. It also returned 4MB/sec and 10MB/sec when copying and retrieving a 690MB video file. Speed dropped for a 623MB mixture of small files, with read/write tests returning 4.1MB/sec and 1MB/sec respectively. As this is an early sample we weren't supplied with any software tools so the WORM functions couldn't be tested.

Whereas Plasmon is aiming UDO mainly at the enterprise, the BW-RS101 targets the SME and is available with a USB 2 interface. Pricewise, there's nothing much between the two formats but the greater performance and superior OS support makes PDD more appealing at the SME level.