February 23, 1998, Issue: 994
Section: News
Fibre Channel at core of technique linking storage right to
nets -- Group pushes compatibility in storage schemes
Terry Costlow
Colorado Springs, Colo. - As suppliers race to gain an edge in the skyrocketing
market for disk arrays and other storage subsystems that attach directly to
networks, roughly 80 major corporations have banded together to form an
industry group to promote compatibility in an arena populated by multiple
architectures.
The quick adoption of this storage technique, which is driven by the emergence
of Fibre Channel and the I2O serial interface, has prompted the formation of
the Storage Networking Industry Association (SNIA). The organization will
meet here March 4 to 6 to set up working groups that will attempt to provide
some common approaches to storage as another node on the network.
In recent weeks, major companies like Sun Microsystems Inc. and Unisys
Corp. have unveiled networked storage subsystems, hoping to position
themselves at the forefront of an emerging market that is still wide open. On
the Fibre Channel front, Vixel Corp. (Bothell, Wash.) will announce plans this
week to acquire Arcxel (Irvine, Calif.), which is sampling its first Fibre
Channel switch. Code-named Galileo, the switch will crown Vixel's line of
Fibre Channel hubs and components.
For these players and several others, the emergence of a storage concept
based around Fibre Channel opens up markets where established players
don't have any more clout than newcomers. Their interest is propelled by a
market of large customers who are trading in Gbyte for Tbyte, with an eye
toward making their vast amounts of storage more readily available to individual
users.
But beyond the use of Fibre Channel-and, perhaps, Gigabit Ethernet down the
road-vendors part ways on just how to accomplish this task. Some designers
are proposing that storage products be linked together on a network of their
own, somewhat isolated from main networks. Others say storage subsystems
and RAID boxes should be attached like any other node, with just a simple
controller that acts somewhat like a server. Some are inserting networking
techniques into storage architectures. Still others feel that thin servers and
client servers will remain a solid part of the networking and storage
environments.
"There are different definitions of networked storage," said Robin Harris, senior
product manager at Sun Microsystems in Palo Alto, Calif. "On one hand is the
network-printer model-just sticking a storage box on the network. On the other,
you can bring network techniques into storage."
Storage today consists of what Harris calls "big, monolithic, inflexible devices.
That's the antithesis of a network, where you have a lot of connectivity and
extra flexibility." Sun's aim in its Intelligent Storage Network, introduced last
month, is to "apply networking techniques inside the storage subsystem," Harris
said.
Some observers contend that the ability to attach storage without using a server
underscores a technological sea change. The rapid increases in disk-drive
capacity have been accompanied by sharp drops in pricing. As more and more
data on a net is accessed by inexpensive microprocessors, some say the
devices that store the data are becoming more important than the CPUs that
retrieve it.
No simple task
"To get that data, you either put a big, bloody server in front of the storage and
create a bottleneck, or you attach the storage directly to the network so
multiple CPUs can talk to the same storage," said Dal Allan, president of
ENDL Consulting (Saratoga, Calif.). "If you have 20 CPUs talking to one
server that has 60 disk drives on it, there are a lot of advantages to ripping out
the server and putting the disk drives on the network."
However, attaching disk storage to the network is not a simple job. Software
changes will be significant. If storage can be accessed by a number of CPUs, it
can also be altered by different CPUs. That can make it tough to maintain data
integrity.
"One of the reasons it's taken so long for OEMs to roll out storage-area
networks is that this is serious data; you can't have someone mucking up a
corporate database," said Brenda Christensen, marketing vice president at
Brocade Communications Systems Inc. (Irvine, Calif.), which makes Gbit
switches. "Some people say this should only be deployed in a homogeneous
environment until the management issues get ironed out."
One missing link, in Christensen's view, is middleware. "Things like distributed
block managers are needed to lock records so you can't have multiple writes to
the same record."
Such concerns, combined with the expectation of stratospheric growth, are
what sparked the formation of SNIA. The founders hope the new organization
can iron out the incompatibilities and establish common approaches to
storage-area networks.
A key problem is that there are several standards, such as Fibre Channel,
Gigabit Ethernet and I2O, that all fit at least some aspects of storage-area
networks. That means different vendors can pick different standards for the
same application. Moreover, certain issues within each of these emerging
standards could lead to problems downstream.
"There are conflicting standards, and some are very loosely defined," said Paul
Borrill, chairman of the SNIA, who is also chief architect at Quantum Corp.'s
Specialty Storage Products Group (Milpitas, Calif.). "No one agrees whether to
use Ethernet or Fibre Channel. Some Fibre Channel products don't talk to
Fibre Channel products from other companies."
But Borrill said the SNIA has no intention of promulgating additional standards
of its own. "If we find things like compatibility [problems], we will go to the
[appropriate standards] group and get them to help. We are not a
standards-making organization," he said.
The SNIA has support from scores of vendors, many of them leaders in
different segments of the storage and networking industries, from systems to
networks to chips. Among them are Compaq Computer, Digital Equipment,
Fujitsu, IBM, Intel and Novell. But despite this impressive lineup, not everyone
believes the industry needs a monitoring board.
"I can't figure out any benefit to that group," said a vendor who declined to be
identified. "Major companies have been working on Fibre Channel for years,
and the Fibre Channel groups have been working with Microsoft and others
since 1996. There's nothing the SNIA will be able to do about much of this-they
won't get much going before 1999, and there will be a lot of products shipping
before then."
Whatever its flaws and virtues, Fibre Channel is at the center of nearly all the
attached-storage schemes that are now starting to ship, though some suppliers
are looking at Gigabit Ethernet for future products. In past years, designers
attempted to provide similar capabilities with SCSI and other interfaces, but
none of those attempts caught the industry's fancy. That's because SCSI was
limited in both bandwidth and attachment capabilities.
"Fibre Channel Arbitrated Loop is the key technology for this," said Sun's
Harris. "It's a very high-speed channel, and it has the networking-style
techniques you need to implement storage networks."
Not only does Fibre Channel support 127 nodes, Harris said, "it supports the
fabric technique and switching." Fabrics and switches make it possible for
several devices to talk directly to one another in networked applications while
also providing flexibility. At the enterprise level, Fibre Channel also makes it
possible to pull distributed storage together. Even down at the disk-drive level, it
provides benefits for the designers of networked storage.
"One thing that's happening is that storage is being consolidated," said Tom
Samulewicz, director of strategic planning at Unisys Computer Systems Group
(Mission Viejo, Calif.), whose NAS2000 came out last month. "If you
consolidate storage, you've got to be sure it's always up. One of the benefits of
Fibre Channel is that drives can be dual-ported, so you've got two points of
entry in case one fails."
Though many of the new attached systems look like servers, with lots of disks,
Samulewicz said they have "attributes that are far different."
Another plus for Fibre Channel is that it lets companies maintain their huge
bases of SCSI storage. Fibre Channel uses many SCSI protocols, so it
provides backward compatibility.
"This is the first time legacy technology is carried forward; almost all the SCSI
applications go forward," said Brocade's Christensen. "There are companies
that do bridges and routers that provide Fibre Channel pipelines into SCSI
storage subsystems, so people can get the benefits of Fibre Channel without
spending a fortune."
The swift emergence of Fibre Channel is opening up the storage market for
newcomers. A host of startups like Brocade, Gadzooks, Vixel and others have
come up with various concepts for building blocks of the networked approach.
At the same time, the new I2O serial interface has made it possible for large
companies that didn't have a strong position in the booming storage-subsystem
market to gain a foothold.
"It may be that a SCSI company had 60 percent of the market, but that won't
necessarily be true in Fibre Channel," Christensen said. "Companies like Unisys
and Digital Equipment can reshape themselves. The market makers won't
necessarily be the same."
Despite the number of approaches to networked storage, long-term goals are
the same. Both independent vendors and the SNIA have a common aim.
"We have a vision that storage and networks can be unified seamlessly, not just
overlapped. There will be a complete convergence," SNIA's Borrill said.
"Storage needs to become a peer with other elements on the network."
Copyright (c) 1998 CMP Media Inc.
New Search | Search the Web
You can reach this article directly here:
techweb.com |
