This article is published @ infomation week.
December 1, 1997
Storage Update: Raising The Ante With Disks
Strolling the aisles at Comdex/Fall can bring unexpected revelations,
including next season's disk innovations
By Simon C. Watkins
s a university professor and IT specialist, I'm always looking for
innovative solutions to help manage the rapid pace of change that
steers my IS enterprise. One of the more perplexing problems I've had to
deal with lately involves a rather unsexy subject: data storage.
However, at Comdex/Fall I found a couple of solutions that adequately
address a problem I'm sure many IT organizations deal with daily.
I'm responsible for the integration of high-end microscopy tools with
computerized data collection, analysis, and storage. I run a moderate-sized
network of computers across four principal platforms: Windows NT, Novell,
Mac OS, and Unix. These computers drive microscopes, collect digital
images, and analyze and store the data. The individual images are generally
about 2 Mbytes in size. But when collected as a series over time or space,
data sets are commonly several hundred megabytes in size. We can store
close to 100 Gbytes on our network. Nonetheless, we find that whatever the
capacity of the online storage space, it will always be full.
Traditional backup tools such as tape are unsuitable, because data will
generally need to be restored to online media for viewing and analysis. We
use recordable CD-ROMs. We bought our first recorder for several thousand
dollars. Today, because of oversupply within the industry, recorders sell for
less than $500 and disks less than $2 (vs. at least $10 in the early years).
Given the inherent portability of the disks between platforms, recordable
CD-ROMs would seem to be an ideal solution. But experience has shown
that this technology has significant limitations, and novel innovative
strategies must be implemented.
First of all, the 650-Mbyte capacity of a CD-ROM is not sufficient when large
image sets are the stock in trade. We burn at least 20 CD-ROMs a week.
For each CD, an image must be built locally on a hard drive and then stored
to the CD, even with a 4x writer. After verification, this process takes at least
90 minutes. I practically need a full-time person simply to archive data.
So I need a solution to my problem. I found two excellent ones at Comdex:
DVDs and removable cartridges, each of which comes with both pros and
cons.
Recordable DVDs, known as DVD RAM (Toshiba's group) or DVD+RW
(Sony and its partners) are rewritable media. DVD RAM stores 2.6 Gbytes
on a single-sided disk or 5.2 Gbytes on a dual-sided disk. DVD+RW holds 3
Gbytes on each side. It is important to recognize that this is the first
generation of the storage media. Even in its first incarnation, the drive has
been priced at about $800 retail and the disks at $20 to $50. In the new
year, it will be possible to store vast amounts of data reliably and
inexpensively using this technology.
Big Step Up
The release of recordable DVDs represents a tremendous step forward in
bulk storage at low cost. The only drawback is their relatively slow read and
write access time. For example, DVDs will be too slow to record video data
in real time. But if cost is less of an issue than speed, another equally
exciting innovation based on magnetic media may be more appropriate.
Removable cartridge systems, meanwhile, use DVD technology and allow
massive storage in a removable form. One cartridge system comes from an
industry leader, Syquest. This drive, the Quest 4.7, will be released next
year. It will be priced at about $600 retail, and store 4.7 Gbytes on each
cartridge, equivalent to a double-sided DVD RAM.
The ultrawide SCSI interface allows a seek time of 12 milliseconds,
equivalent to a moderately fast nonremovable drive. This is a significant
speed improvement over DVD, though at a cost-the cartridges are expected
to sell for about $199.
I expect to implement both DVD and removable cartridges, using the higher
recording speed of the magnetic devices to make online recordings and
short-term archives of video or other high-throughput data. These disks may
then be used to master the more stable and slower optical storage media for
long-term storage.
Simon C. Watkins, Ph.D., is an associate professor and the director of the
Center for Biologic Imaging at the University of Pittsburgh. He can be
reached via his Web site at sbic6.sbic.pitt.edu. |
