Long term outlook for magnetic and optical disk storage technologies

Abstract

Ten years ago, as rewritable optical disk products were first being introduced into the marketplace, it was common to compare magnetic and optical disk technologies in terms of their areal density metric, and to speculate about the demise of magnetic hard disk drives (HDDs) because ofthe superior densities of optical disk drives (ODDs). Now, in 1997, we can look back with a quite different perspective about the HDD funeral which never occurred, and about the relative roles which have been carved out for HDDs and ODDs. Of greater interest, we can also look forward with an eye to the likely evolution of these devices for the next ten to fifteen years. HDD technology has survived and prospered because it aggressively advanced on several parallel fronts: areal density, volumetric density, reliability and, simultaneous with and deriving from all these advances, rapidly declining end user cost. These advances made it exceedingly difficult for ODDs to capture significant market share from HDDs via a direct frontal assault. As history has played out so far, ODD products have succeeded only in those market niches where they have exploited their unique capabilities: removability with random access (as in jukebox library systems), and mass information replication and distribution (as in CD-ROMs). For HDDs, future progress means continuing to advance areal and volumetric density and performance, while continuing to drive costs down. For ODDs, future progress also means continuing to advance capacities and to decrease costs, but as it has in the past, ODD technology will need to play to its own unique strengths. Clearly one route to capacity advances will be to continue to decrease the diffraction limited optical spot size through use of shorter wavelength lasers and higher numerical aperture optics.