Enterprise storage might look like a problem thats been solved in principle, requiring only continued refinement of proven technologies combined with the careful management thats needed to minimize costly data glut. IT system builders must look ahead, however, to the dead end on the path of hard disk evolution and start to think now about other pathways that can be explored as storage volumes inexorably grow.
Intelligent choice among storage technologies involves a careful balance among four distinct, often-contentious characteristics: total capacity, access speed (for both random and sequential access, depending on the application), physical density and storage media lifetime.
Improvement in any one of these attributes will often come at the expense of others. Emerging alternatives to magnetic disk have complementary strengths and weaknesses. Every enterprise needs its own carefully tailored portfolio, meeting not only volume requirements but also operational and even regulatory needs.
A study by the University of California at Berkeley in 2000 estimated the worlds production of new bits to store as being on the order of 250MB per person per year and projected that this would almost double every year. The same groups follow-up study in 2003 confirmed that per-capita data production two years later had more than tripled to at least 800MB per year, with the volume of data on the Web alone comprising 17 times the volume of the Library of Congress print collection.
To estimate future storage needs, by simple extrapolation of the exponential trend, is cause for amusement or despair. Sometime before 2100, one would conclude, the entire crust of Earth will be representing data at a (purely theoretical, so far) density of one bit per atom. Parsimonious data retention policies, as well as aggressive rich-media compression algorithms, will have to be thrown at this problem, along with every possible improvement in storage technology.
The search for greater real-world storage density, meanwhile, is rapidly taking engineers into the realm of nanoscale devices—devices whose dimensions are on the order of nanometers, or millionths of a millimeter. IBM, for example, is already fabricating electromechanical storage systems whose probes are only 10 nm in diameter. A human hair is about 6,000 times as coarse. Even in current hard disk assemblies, component dimensions and tolerances that are on the same order of size as individual atoms are already becoming the rule.
Enterprise IT buyers are most concerned, at least directly, with finances rather than physics. For the past two decades, dollar-denominated measures of storage performance have looked pretty good. Specific figures vary hugely, depending on the level of device packaging that one uses for purposes of estimating costs, but the downward trend of storage cost "is clearly exponential," said Steve Gilheany, senior systems engineer at document management consultancy ArchiveBuilders.com, in Manhattan Beach, Calif.
Gilheanys year-2000 analysis, combining historical trends and projected technology developments, projected the price of desktop-grade magnetic data storage at about 2 cents per gigabyte in 2010. Mainframe-grade devices would sell for approximately 12 times that cost, he estimated, with intermediate grades of equipment at varying levels of speed and RAID protection sprinkled along the continuum in between.
If anything, Gilheany noted in a discussion this month with eWEEK Labs, the rate of price decline had already been accelerating during the most recent years from which his cost-trend data was taken. It now appears to us that the recent explosion of consumer-device demand has steepened the decline in magnetic storage costs still further. Gilheany, in 2000, projected a cost in 2004 of 77 cents per gigabyte, but a 250GB drive is already available as of this writing for as little as 55 cents per gigabyte.
At the risk of ruining a good party, however, the scientists have some truly bad news. Barring the development of downsized atoms, or the multivendor approval of a new set of physical laws, the shrinkage of magnetic storage has a hard stop at around 60GB per square inch. Attempting to store bits more densely, theorists believe, will be futile—random reorientation of magnetic domains will bury data in the resulting noise.
Its not yet possible to declare the question closed, because tuning the magnetic properties of materials can sometimes seem more like alchemy than like conventional materials science. The fabrication techniques available to storage-device designers include the construction of multilayer films that are literally just a few atoms thick, allowing intricate combinations of materials with sometimes surprising results.
Past experience does suggest, however, that a stable magnetic storage medium may also be a sluggish one: If a material tenaciously maintains its magnetic state despite the forces of random disturbance, it may also be hard to change that state on purpose—slowing the materials response in data-rewriting operations.