As computers have grown larger in processing power yet smaller in size, the need to store data in evermore dense areas has become paramount. This need will soon lead disk-storage manufacturers to face a new problem: the superparamagnetic effect (SPE).

In essence, the SPE is a physical phenomenon that occurs at the atomic level of a bit of data stored on a disk-storage medium. As each atom of each bit of data spins to maintain its magnetic property (either 0 or 1, off or on), it generates a certain amount of thermal energy. As more bits are crammed together, their thermal properties begin to affect the thermal properties of adjacent bits. When this energy matches the ambient thermal energy of the area surrounding the magnetic bit, the property of the bit can fluctuate between off and on at random, corrupting the data stored there. This is the SPE, and industry experts estimate that at the current rate of storage miniaturization, manufacturers could run up against the SPE barrier as early as 2005.

Today’s storage-technology companies are aware of this limitation and are being forced to come up with new, innovative data storage and retrieval methods that are not affected by the SPE. That’s why companies such as IBM, Lucent Technologies, Seagate Technology, and Hewlett-Packard, to name just a few, are working feverishly to develop the next latest and greatest storage and retrieval media and techniques. With that in mind, I thought it would be interesting to take a look at some of the technologies they are working on to give you an idea of where the industry may be headed. Who knows? Someday, some of these technologies may even make it into the AS/400 storage arena.

Holographic Storage

One method of data storage and retrieval currently being worked on is data storage through holography. This type of storage uses a medium, such as lithium niobate crystal cubes, to potentially store trillions of bytes of data, or the amount of data equivalent to millions of average-size books, in a space the size of a sugar cube. Using holographic storage involves imprinting data onto the storage medium by passing an image of that data through a spatial- light modulator. The light’s (data’s) properties are identified by two laser beams whose interference with each other and interference with the data’s imprint correspond to make a unique pattern.

This combination of the data pattern and conflicting laser beams is all imprinted on the storage medium. When it comes time to retrieve the data from this medium, the data imprint is illuminated by a laser beam whose exact properties (intensity, angle of reflection,

etc.) match one of the original laser beams. From this, the second laser beam can be reconstructed, and the data becomes instantly identifiable and available. What this means in a real-world application is that data can be correlated based on its actual contents in storage.

Contrast this to the current method, which involves retrieving a bit of data by its address in storage and then comparing that bit with another bit whose values are retrieved from a specific storage address. In other words, the data content is known based on the properties of the original data imprint and laser beams stored with that data. Actual comparisons can be made “in place,” significantly improving data-access speeds.

Punch Cards to the Rescue!

IBM Zurich has invented a new prototype based on the old punch card and has named it Millipede (for the number of styli it uses, which are arranged in a 32 x 32 array). This technology uses the old punch card technique of having a pattern of holes on a flat surface. Today’s version, however, uses plastics and the concept of a stylus, much like that used with a phonograph record.

In a phonograph, the stylus, or needle, reads the grooves in a record; in the new punch card technology, IBM uses a stylus to read indentations in a plastic polymer. The stylus, which has a radius of only 20 nanometers, is moved across the flat polymer surface. When it comes time to write an on or off bit, the stylus is heated to 400º C to melt the surface of the polymer. A series of these melted indentations in the surface indicates a string of 0s and 1s. When the Millipede device reads from the medium, the stylus is heated to only 350º C (to keep it from melting the polymer surface) and again moves across the surface. When it encounters a dip where it previously wrote (melted) a bit of data, it falls into this indentation and the stylus head cools slightly. As this happens, the heat change is detected by the stylus and transmitted as an electrical impulse, thereby indicating to the reader the content of the dip. Although, this technology is a reality in the lab, its commercial outlook is rather slim at the moment.

Ideas, We’ve Got Ideas!

As science learns more about the universe we live in, you can bet that this information will eventually be incorporated into items we use on a daily basis. In the area of data storage and retrieval, some of these futuristic concepts are already proving viable and may appear on the commercial scene sooner than we think. Someday, the concept of an AS/400 the size of a wristwatch may become a reality. For more information check out the article “Avoiding a Data Crunch” by Jon William Toigo in the May 2000 issue of Scientific American. You can also point your browser to www.stormgt.org.

Shannon O'Donnell has held a variety of positions, most of them as a consultant, in dozens of industries. This breadth of experience gives him insight into multiple aspects of how the AS/400 is used in the real world. Shannon continues to work as a consultant. He is an IBM Certified Professional--AS/400 RPG Programmer and the author of an industry-leading certification test for RPG IV programmers available from ReviewNet.net.