The future of Magnetic data storage

The future of Magnetic data storage - The future of...

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by D. A. Thompson J. S. Best The future of magnetic data storage technology In this paper, we review the evolutionary path of magnetic data storage and examine the physical phenomena that will prevent us from continuing the use of those scaling processes which have served us in the past. It is concluded that the first problem will arise from the storage medium, whose grain size cannot be scaled much below a diameter of ten nanometers without thermal self-erasure. Other problems will involve head-to-disk spacings that approach atomic dimensions, and switching-speed limitations in the head and medium. It is likely that the rate of progress in areal density will decrease substantially as we develop drives with ten to a hundred times current areal densities. Beyond that, the future of magnetic storage technology is unclear. However, there are no alternative technologies which show promise for replacing hard disk storage in the next ten years. Introduction Hard disk storage is by far the most important member of the storage hierarchy in modern computers, as evidenced by the fraction of system cost devoted to that function. The prognosis for this technology is of great economic and technical interest. This paper deals only with hard disk drives, but similar conclusions would apply to magnetic tape and other magnetic technologies. Holographic storage [1] and microprobe storage [2] are treated in companion papers in this issue. Optical storage is an interesting special case. If one ignores removability of the optical medium from the drive, optical disk storage is inferior in every respect to magnetic hard disk storage. However, when one considers it for applications involving program distribution, or for removable data storage, or in certain library or “jukebox” applications where tape libraries are considered too slow, it can be very cost-effective. It dominates the market for distributing prerecorded audio, and will soon dominate the similar market for video distribution. However, it remains more expensive than magnetic tape for bulk data storage, and its low performance and high cost per read/write element make it unsuitable for the nonremovable on-line data storage niche occupied by magnetic hard disks. The technology limits for optical storage [3] are not discussed in this paper. The most important customer attributes of disk storage are the cost per megabyte, data rate, and access time. In order to obtain the relatively low cost of hard disk storage compared to solid state memory, the customer must accept the less desirable features of this technology, which include a relatively slow response, high power consumption, noise, and the poorer reliability attributes associated with any mechanical system. On the other hand, disk storage has always been nonvolatile; i.e., no power is required to preserve the data, an attribute which in semiconductor devices often requires compromises in r Copyright 2000 by International Business Machines Corporation. Copying in printed form for private use is permitted without payment of royalty provided that (1) each
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The future of Magnetic data storage - The future of...

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