Take Care to Follow Right Storage Path

This, therefore, raises the question of maintaining a balance between storage volume and storage bandwidth. Even if one could store, hypothetically, a terabyte of data on one magnetic platter the size of a quarter, the resulting device would require a blistering data transfer rate of 776M bps (pushing the next-generation limits of the IEEE 1394b FireWire standard) just to back it up in a leisurely 3 hours.

By 2010, even consumers might sneer at this proposition. In what one might imagine as a video version of Apple Computer Inc.s iPod, for example, the storage device just described would hold only about 100 hours of MPEG2-compressed high-definition TV content. Before anyone dismisses such a product concept as fanciful, note that desktop hardware vendors are already paving the way. Sony Corp., for example, announced this month a desktop system with four 250GB hard drives: two for normal applications and two more dedicated to TV program recording with a capacity of 19 hours per day for seven days on six concurrent channels.

Clearly, new frontiers must be found.

Microsoft says its portable video players will be designed with at least 125GB of storage capacity by 2007. Click here to read more.

If bits per unit area are disks fundamental physical limit, it seems logical to explore the storage of data in a volume instead of on a surface. Thats the essential attraction of holographic storage, which creates a distinct optical interference pattern at the intersection of two interacting laser beams.

With suitable hardware, data can be read or written simultaneously at multiple locations within a single medium. Without the inertia of a magnetic drive heads mechanical actuators, the agility of the massless laser beams enables high performance during sustained random-access operations.

Moreover, the nature of the holographic interference process enables new modes of associative retrieval, effectively measuring the similarity—at many points throughout a volume of an optical storage medium—to a given reference pattern. The best-match value can then be retrieved, without prior knowledge of its location and without need for time-consuming, item-by-item examination.

This doesnt merely change the economics of storage; it also suggests fundamentally different approaches to application development models in business intelligence, homeland security and other domains of considerable interest to enterprise and government IT planners.

After decades of anticipation, holographic technologies are condensing from vapor to reality: InPhase Technologies Inc. plans to deliver its pioneering Tapestry 200-R holographic storage units next year, with each providing 200GB of recordable (but not yet rewritable) storage at a rate of 20MB per second and a removable-media cost of 25 cents per gigabyte—about twice the current cost of recordable DVD.

The road map of this Lucent Technologies Inc. venture forecasts the offering of rewritable media by 2008, with data rates of 40MB per second. Planned capacity expansion, going hand in hand with improved data throughput, could yield a 1.6TB recordable device operating at 120MB per second by 2010.

Marking a much greater departure from electromagnetic storage traditions is IBMs microelectromechanical Millipede technology—in effect, a fantastically scaled-down computer punch card.

A Millipede drive moves a brushlike apparatus, supporting a grid of several thousand submicroscopic probes in two dimensions across a film of thermoplastic material on a silicon foundation thats only a few millimeters square. Each of the 10-nm probe tips remains within a neighborhood about 100 microns square, minimizing power-consuming movement of the probe grid. Each probes neighborhood can store thousands of rewritable bits by forming tiny pits in the plastic, or reforming its flat surface, using the electrically wired probes local application of heat and pressure.

Each probe tip can achieve a rewritable data rate of well over a megabit per second, with a storage medium lifetime of at least 100,000 cycles at any given storage location. By using thousands of independently addressable probe tips in each device, Millipede offers highly scalable parallel data access. Sources close to the project have suggested that a 4,096-tip probe may already be functioning in a demonstration device, with overall data transfer rates on their way toward a target of 800G bps.

Next page: Data transfer rate vs. power consumption.