Phase-change drives can the way you back up data
Although it hasn't exactly made a big splash yet, there's an alternative to
CD-recordable technology that just might suit your agency better. It's called phase-change
Phase-change drives originally were supposed to be cheaper than CD-R drives, but lately
magneto-optical and CD-R products have come down so much in price that the difference
isn't as great as anticipated.
For about half the cost of a CD-R drive--which creates and reads CD-ROMs--you can buy a
phase-change or PD (phase-change dual) drive that not only reads standard CD-ROMs,
including CD-R disks, but also creates its own rewritable, non-standard optical disks.
Blank, 664M phase-change disks now cost about 10 times more than same-capacity CD-R
blanks, but they can be'20erased and rewritten up to a half-million times, according to
manufacturers. That makes them highly useful for periodic backups but less suited for
archiving than CD-R.
The PD disks are the same size as CD-ROMs and come in those familiar rectangular
plastic cases. The cost per megabyte is close to that of magneto-optical or the new
SyQuest Technology Inc. and Iomega Corp. rewritable, random-access drives. However, CD-R
still has a bigger installed base and lower-priced media than these other removable-media
I see as PD's biggest disadvantage the fact that the disks, once created, can only be
read by a PD recorder. So if you use PD for backup, you're in the same boat as a tape
backup user whose only drive breaks down --you have the backup but can't do anything with
CD-R disks can't be reused, but they can be read by tens of millions of existing CD-ROM
drives--an important advantage for some organizations, and the main reason CD-R remains
the best optical publishing medium.
Whether the shortage of compatible drives is a significant disadvantage to you depends
partly on whether your organization can afford duplicate PD drives--remember, you could
buy two for the cost of a single CD-R drive.
Because PD behaves like a magnetic hard drive, you can make hundreds or thousands of
backups to the same disk, overwriting old data each time . Obviously, two or more disks
should be rotated to ensure reliable backup.
If you make lots of backups and reuse the media, PD could quickly pay for itself by
saving the expense of one-shot CD-R media. For a single daily backup, say 22 times per
month, CD-R blanks would run you about $200 a month. Two PD disks for alternate-day
backups would cost only about $90 for the pair. In the course of a year, you'd save more
than $1,000 on media--twice the price of a second backup PD drive.
Panasonic Communications and Systems Co. of Secaucus, N.J., and Plasmon Data Inc. of
Milpitas, Calif., sell PD products based on Matsushita's LF-1094 drive, with
understandably similar performance. Panasonic's PD/CD-ROM Drive LF-1000AB is available
with CorelSCSI software for MS-DOS, Windows 3.x and Macintosh PCs. A PD drive comes built
into Panasonic's new CD-62 multimedia notebook.
Smart and Friendly Computer Products of Chatsworth, Calif., sells the PD QUADe drive
with CorelSCSI software for MS-DOS, Windows 3.x and Mac, as well as Adaptec's EZ-SCSI Lite
software for Windows 95. Internal and external versions are available, but so far there's
no plug-and-play installation for these products.
John McCormick, a free-lance writer and computer consultant, has been working with
computers since the early 1960s.