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SANs come up to speed

SANs come up to speed

Storage networking equipment vendors are preparing a slew of new Fibre Channel switches and host bus adapters that can effectively double the speed of current storage-area networks (SAN) to 4Gbit/sec. Products based on the 4Gbit standard, first advocated by chip makers last year and approved by the Fibre Channel Industry Association (FCIA) and the American National Standards Institute last June, are slated to roll out this year. The technology could serve as an interim migration step to products based on the 10Gbit/sec. Fibre Channel specification approved by the FCIA last November.

But not all users are convinced that more speed is better, especially where application servers are the bottleneck. "On the fabric side, it's screaming . . . but you'd saturate your (server) bus long before you'd saturate a 1Gbit or 2Gbit Fibre Channel connection," says Gary Pilafas, senior storage and systems architect at UAL Loyalty Services, a unit of United Air Lines.

Mike Bennett, a senior network engineer at Lawrence Berkeley National Laboratory in California, believes that new servers being offered with 64-bit processors and faster internal bus designs will require more than the additional bandwidth being offered by 4Gbit Fibre Channel switches, RAID controllers and host bus adapters for SANs.

"Two years out, is there going to be a market for it? I'd say no doubt. It's like garage space: If you have it, you'll fill it," Bennett says.

By that time, however, 4Gbit products will face competition from devices based on a faster 10Gbit standard. In fact, as vendors begin volume shipments of 4Gbit products later this year, they'll be introducing early 10Gbit products as well.

Bennett says 10Gbit Ethernet will challenge Fibre Channel as an alternative storage interconnect if Fibre Channel doesn't keep up, so a leap to 10Gbit is a must. But 4Gbit devices offer critical advantages: Analysts and vendors say the 10Gbit/sec. devices won't be backward compatible with current 1Gbit or 2Gbit products. And they're expected to cost about US$5,000 (AUD$6633) per port -- five times as much as current 2Gbit devices.

In contrast, the upcoming 4Gbit devices are expected to cost about US$1,000 per port, the same as their 2Gbit cousins.

As a result, analyst Rick Villars at market research company IDC inthe US, is bullish on the standard's prospects. He predicts that 4Gbit products will hit the market in the third quarter but account for just 10 percent of the market within the first 12 months. After two years, however, he expects that number to leap to 90 percent as competitively priced 4Gbit products replace slower offerings.

"They're going to be the best technology at the lowest price," Villars says.

Meanwhile, high prices and backward-compatibility concerns will limit the appeal of next-generation 10Gbit devices. "You have to replace anything that the 10Gbit technology touches with all-new 10Gbit equipment," says Villars.

The third option

Aware of these limitations, vendors came forward with the interim 4Gbit standard. And hedging their bets yet again, SAN equipment vendors have another interim Fibre Channel standard in the offing. Disk drive manufacturers are rallying around a newly proposed 8Gbit specification, and SAN managers could see products within three years, according to manufacturers.

Skip Jones, chairman of the FCIA's Speed Forum, says the organization held its first meeting on 8Gbit Fibre Channel last month. "If we get out there three years, and you're still paying a huge premium for 10Gbit technology and you want that backward compatibility, that's where 8Gbit will be attractive," he says.

For now, the focus is on 4Gbit products. Several vendors, including San Jose-based Hitachi Global Storage Technologies, the disk manufacturing arm of Hitachi Data Systems (HDS), have announced 4Gbit Fibre Channel offerings.

So where does that leave 10Gbit Fibre Channel? Despite the cost and compatibility issues, vendors see a place for the developing standard in high-end SANs. Hubert Yoshida, chief technology officer at HDS, says 10Gbit products will serve as an interswitch link that can cobble together many switches in a SAN fabric while using fewer ports. He also sees it as a way to create many virtual ports over one physical switch port. "Through the same physical port, we can allow up to 128 different users," he says.

Arun Taneja, an analyst at The Taneja Group in the US, predicts that the demand for 10Gbit Fibre Channel will be enormous, both for connecting internal disk drives to RAID controllers and for interswitch links in corporate SANs.

"There's no large enterprise I know of in the Fortune 300 or 400 range that doesn't have a massive number of Fibre Channel switches at this point in time. As they replace those switches or directors with 4Gbit Fibre Channel ports, there's no question they'll need multiple 10Gbit ports to balance that out," Taneja says.

The 4Gbit players

Although some vendors are preparing 4Gbit Fibre Channel devices for release as early as this summer, others are more cautious.

Hitachi Data Systems has begun joint testing of new 4Gbit/sec. hard drives with resellers and expects those devices to be available by summer.

Emulex has announced its embedded 4Gbit storage switching technology and has plans for a host bus adapter this year and a 10Gbit HBA in 2005.

QLogic currently offers a switch that has two 10Gbit ports for interconnections between switches. By midyear, it plans to ship 4Gbit HBAs and switches that support 4Gbit/sec. and 10Gbit/sec. speeds.

Cisco Systems hasn't yet committed to producing 4Gbit products, but it has announced support for the 10Gbit standard. It plans to make a 10Gbit module available on its MDS 9000 SAN switches sometime this year.

Brocade Communications Systems doesn't plan to begin testing 4Gbit and 10Gbit switches with storage device manufacturers until 2005.

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