On the high-DENSITY horizon - Technology Information

Emedia Professional, Feb, 2000 by David Doering

Enterprise network storage requirements currently increase by 100 to 200 percent per year. Removable storage must follow hard drives' lead in accommodating these needs, and meet the expectations that the fixed devices set. At 650MB, CD-R was once highly competitive as a storage medium, but now draws its considerable cachet primarily from its advantages as a distribution medium. DVD-RAM offers a more reasonable removable storage complement for today's 5 to 10GB hard drives.

But the PCs we buy increasingly sport hard drives up to 18GB, with higher capacities to follow. How can a disc supplying 2.6GB of storage be attractive for long in that environment? Consider that this is four DVD-RAM discs per workstation. What about a network of a dozen workstations?

Fortunately, there's help on the horizon for higher density storage, thanks to a range of new technologies in the 120mm physical format that continues to serve so well.

Blue-laser technology has long been heralded as a follow-up to the ubiquitous red-laser in CD and DVD drives. Unfortunately, it remains a no-show in commercial circles. Mechanically, a blue-laser DVD drive would be identical to today's red-laser units except for the laser itself. The blue laser's tighter beam, 414-430nm versus 635,650nm for red, provides the higher densities. A 120mm disc read using this beam example could hold about 18.8GB per layer, per side--four rimes DVD's 4.7GB.

So what's holding them back? Heat. Getting the lasers to function reliably at room temperature has been almost a five-year struggle. Finally, in October 1999, Nichia Chemical Industries of Japan (http://www.nichia.com) announced a breakthrough with the commercial release of a violet laser. Violet-laser beams are even tighter than blue--405nm--and thus they leapfrog blue with 27.8GB per layer on a 120mm disc.

But don't rule out MO just yet. It's got one last hope--Maxoptix' new Optical Super Density (OSD) technology (http://www.maxoptix.com). OSD promises a 40GB capacity and a 30MB/sec transfer speed, combining tape-like high capacity with hard disk-like speed. This is partly achieved through some sleight of hand: with Surface Array Recording (SAR), both sides of the disk can be accessed simultaneously, which doubles capacity and speed for each disk.

OSD also boasts a new lens, allowing a tighter beam for recording; new media, allowing the lens to be much closer to the disc (through an improved coating); and a new recording method (MFM) for single-pass recording.

A 40GB/disc capacity with a high transfer rate is certainly desirable in a future network storage solution. The drawback here is that it is proprietary. The drives are not backward-compatible with other MO types, and other vendors are no more likely to embrace Maxoptix' design as the future industry standard than they have been to collude with other renegade formats like Pinnacle's 4.6GB or NEC's ASMO.

Perhaps the most exciting high-density storage announcement in the last year comes from Israeli startup C-3D (http://www.c-3d.net). In September 1999, C-3D demonstrated a new recording technology called Fluorescent Multilayer (FM). This new FM method currently allows up to 10 layers of recording on each 120mm disc. With 14GB per layer, this adds up to a total of 140GB for the whole disc.

With CD and DVD technology, data is recorded and read through reflective technology. It shouldn't surprise us then that as the number of layers increases with these discs, it becomes increasingly difficult to read them.

With FM technology, the recording material is made to emit light, not reflect it. This fluorescence of the media enables writing and reading of multilayer structures with much greater storage capacity. C-3D claims it is possible to have not just 10, but 100 layers per disc. This would equal 1.4TB of capacity on a single 120mm disc--equivalent to an entire 300-disc jukebox today. (A jukebox filled with 300 of these discs would hold a half-petabyte of data, enough to make even a staunch StorageTek silo fan take notice.)

The challenge for C-3D is to move this technology out of the lab and into production. They hope to have commercial units out in 12 months for FM-ROM, FM-Worm, and FMPC Card drives. They are also pursuing an aggressive licensing program to encourage other hardware vendors to incorporate FM technology in their drives.

Finally, long-discussed Norsam (http://www.norsam.com) is progressing on its HD-ROM technology. HD-ROM uses a particle beam, rather than a light/laser, to write data. The disc itself would be metallic, rather than plastic, which promises a longer shelf-life than CD or DVD.

The tighter focus of the electron particle beam pushes the density up to 200GB per 120mm disc. Norsam hopes to have recording speeds up to 30MB/sec, with read speeds comparable to CD (about 6MB/sec.) Since it uses a metallic medium, the HD-ROM drive would naturally be a WORM system.

Rather than a standalone drive, Norsam is looking at a small RAID box or jukebox-style system supporting 30 ten-disc modular readers. This system would provide about 60TB of storage, so it will definitely fit well with future requirements when it arrives in 2003.