Not sure if this has been posted for consumption. It is no longer if, now it is definetly when...
Fibre Channel strides forward, as 1394 falters
By Terry Costlow
LAS VEGAS -- Far more new Fibre Channel disk-drive products will be
displayed at Comdex/Fall than rival 1394, or Firewire, drives.
Just about anyone involved in mass storage will be rolling out Fibre
Channel products at Comdex this week. Those keeping track say
introductions will be measured not by tens but by scores. That's a sharp
contrast to the support for Firewire.
One of the lingering questions about Fibre Channel was answered last
month when a standards committee folded a plan to merge Fibre Channel
with IBM's Serial Storage Architecture. That move clears up minor
concerns about backwards compatibility with the versions of Fibre
Channel that are being shipped today. Some of the details that might
have been required to integrate SSA and Fibre Channel would have changed
cabling requirements, so the standards committee has decided not to
pursue that path. A little over a year ago, Seagate, IBM and others
decided that merging SSA with Fibre Channel in future generations would
provide the best performance.
The decision not to follow that plan will probably have only a minor
impact on the acceptance of Fibre Channel. Right now, it has the
appearance of a snowball at the top of a hill, with several disk-drive
companies moving to push it downhill.
By contrast, disk-drive makers were getting interested in 1394 during
the summer. But that interest has fallen as quickly as the leaves.
Samsung Storage System Division (San Jose, Calif.) is one of the few
that will show a 400-Mbit/second 1394 drive here, and its support isn't
exactly bullish.
"Right now we're working with a two-chip solution for the link and
physical layers so we can gain experience with 1394, but our product
will be a one-chip solution when it's out next summer," said John
Glavin, senior vice president at Samsung's R&D Center. "I think 1394
makes sense only when Device Bay comes out."
Device Bay is a concept being promoted by Compaq and others in which all
attachments to a PC will fit into a peripheral box that attaches to the
CPU via 1394 and the Universal Serial Bus. When it comes out, possibly
late next year, drive makers may start shifting to 1394 in a slow but
serious fashion. By then, the 800-Mbit/s version of 1394 should be
shipping. Until then, they don't see much interest from the PC providers
that will be the consumers of 1394 drives.
"Even at 800 Mbits/s, 1394 only adds cost," Glavin said. "For the
desktop, it doesn't gain you a lot of performance over UltraDMA (the
latest version of IDE/ATA), which runs at about 240 Mbytes/s. The
channel isn't the bottleneck, it's the rate off the head and disk that
is the bottleneck. [The] 1394 gives you [a present] advantage until bus
bandwidth is the bottleneck."
As long as the IDE controllers integrated into core logic devices
provide a disk interface that is essentially free, 1394 proponents will
have a tough time convincing the system designers to add 1394 to the
motherboard, and those system designers' decisions drive disk makers.
Some other peripherals, such as cameras, are expected to boost 1394
usage, but those products will typically attach to the PC via an add-in
board, not a chip on the motherboard. Without Device Bay, there will be
little impetus for drive makers to adopt it.
"Device Bay is seen by many as the thing that breaks the chicken-and-egg
cycle from the standard we've had over a decade with ATA," said Tim
Orsley, product planning manager at Quantum Corp. (Milpitas, Calif.).
"The main question is how quickly this type transition occurs. The
momentum for ATA is so strong that they will coexist for quite a while."
Indifference to Firewire
Chip makers, who typically have to move a bit earlier than the drive
makers they supply, are equally indifferent.
"[The] 1394 has a spot to fill, but it is still coming slowly even where
it is clearly needed," said Skip Jones, director of planning and
technology at Q-Logic (Costa Mesa, Calif.). "It solves the problem in
digital consumer-product trends, like when you have a camera and you
want to download pictures to your printer or computer. But some of these
products are using SCSI. We are basically sitting on our 1394
development until we see the market start to turn."
That turning point has already come for Fibre Channel, the
high-performance serial link that is in line to replace SCSI. A number
of Fibre Channel products are already being shipped, and several more
will be unveiled at Comdex. Some observers see the recent announcement
of a Fibre Channel disk drive from IBM Storage Systems Division (San
Jose, Calif.) as a key sign of support, particularly given the recent
decision by the standard committee to drop the proposal to merge SSA and
Fibre Channel.
"Given the politics and passion that have been going on, this is quite a
significant turn," Jones said. "IBM's drive is not Fibre Channel EL [the
proposed name for the Fibre Channel-SSA merger]; it's just Fibre
Channel. That means all the major drive and system companies are
supporting Fibre Channel for next-generation products."
Though most high-end disk drive makers have unveiled at least one Fibre
Channel drive, the market for those products is not expected to take off
for a while. The earliest applications of the serial link will be to
link large numbers of SCSI drives, often configured in a RAID
environment, to the host. Fibre Channel links will be outside the
storage box, not inside it.
"The usage of external Fibre Channel interfaces will become normal in
1998, but it won't be normal inside the box until 2000 or so," said Dal
Allan, president of ENDL Consulting (Saratoga, Calif.). "Fibre Channel
starts saving people money when they get beyond 40 to 50 disk drives. At
that point, you're looking at four SCSI or only one for Fibre Channel."
While the long-term outlook is bullish, even the most ardent Fibre
Channel proponents don't expect to see OEMs drop SCSI products quickly
just so they can tout Fibre Channel products. Ultra2SCSI products have
close to the same speed as Fibre Channel, and they let users stick with
the same firmware and cabling that has been used with previous
generations of parallel SCSI.
"If you take a Fibre Channel Arbitrated Loop system that is shipping
today, a well-configured UltraSCSI subsystem will outperform it in I/Os
per second," said Dave Coombs, vice president of storage sales and
marketing at Digital Equipment Corp. (Shrewsbury, Mass.). "In bandwidth,
Fibre Channel's 100 Mbytes/s will outperform UltraSCSI's 80 Mbytes/s.
Today, the most robust solution for 90 percent of the market is still
UltraSCSI."
That said, Digital is rolling out Fibre Channel subsystems. Early
adopters will be implementing the technology this year, and usage of the
interface is expected to become the proverbial racing snowball in the
next few years. Next year, a 200-Mbyte/s version of the interface will
provide more than double the speed of parallel SCSI products, signaling
the beginning of the end for the long-standing parallel interface. Even
at 100 Mbytes/s, Digital marketers said, there are solid reasons for
moving to Fibre Channel.
"There are companies that are bandwidthed out, and they need to go 20
percent faster than they can with UltraSCSI," said Dave Guy, director of
Digital's Storage OEM business. "Another thing Fibre gives you is 10
kilometers in distance, vs. 25 meters with SCSI. Another key aspect is
connectivity, where Fibre Channel wins at 128 drives to 16 for SCSI." |
