Finishing my thought....
A helical scan recorder like 8mm, on the other hand, doesn't face those issues because the data rate is decoupled from relative tape speed (tape speed * cylinder speed). In other words, one can generally increase the data rate by increasing the number of heads and keeping relative tape speeds relatively constant. Toshiba and BTS, for example, have a D6 HDTV recorder that has speeds of up to 150 MB/sec that uses 64 recording heads! Helical scan recorders are also becoming more and more reliable every year. For example, in order to counter the perception that helical scan recorders are less reliable than linear recorders, Sony has included a self-cleaning mechanism in AIT.
Perhaps, one factor in IBM/SEG/HWP's decision to use helical scan may be the fact that there are tremendous economies of scale already in place for helical scan recorders, which draw on its roots in the consumer electronics mass market. The DVD is eventually going to render helical scan recorders obsolete in the consumer electronics space and mass storage is a natural market that the Japanese manufacturers can use to extend the useful lives of their state of the art tape drive manufacturing facilities.
For example, under Morita, the founder, Sony was content to being Exabyte's contract manufacturer for 10 years. When Idei took over in 1995, he quickly marshalled his forces to enter the mass storage business directly. In a scant 2 years, Sony now has DAT (<1/4"), AIT (8mm), DTF (1/2"), D1 (3/4") and its robotics technology that allows it to build Petasites (1 Petabyte = 1000 Terabytes).
All that said, DLT is the sub-$10,000 tape drive with the momentum in the sweet spot of the market that is going to expand even more with the kind of bandwidth that is going to be introduced into the networks. It should really come as no surprise that you have troikas like IBM/SEG/HWP and others working furiously to participate more vigorously in that sweet spot. One should also expect that the requirements of this sweet spot will change as faster processors, faster networks, faster storage devices and other variables combine to create new and perhaps, more demanding ways of doing things like backup. |
