Several storage vendors are testing new devices that could double the throughput of Fibre Channel storage-area networks (SAN) and network-attached storage boxes from the current 2Gbit/sec. rate.

The faster 4Gbit/sec. standard was approved last June by the Fibre Channel Industry Association, but vendors hesitated to begin developing the faster technology because of a slump in storage purchases. Now, makers of Fibre Channel host bus adapters, switches and disk drives say devices adhering to the new standard are on the horizon and will cost roughly the same or a little more than 2Gbit/sec. hardware.

At the same time, some vendors are releasing products with 10Gbit/sec. capabilities well ahead of a planned standardization of that technology in 2006. But analysts and vendors this week said the 10Gbit/sec. devices won't be backward-compatible with 1Gbit/sec. or 2Gbit/sec. products and will cost about five times as much per port as current 2Gbit/sec. and upcoming 4Gbit/sec. devices, or US$5,000 a port.

Even if costs remain the same, Gary Pilafas, senior storage and systems architect at UAL Loyalty Services, a unit of United Air Lines, said he's wary of installing 4Gbit/sec. devices on his SAN. That's because the application servers he backs up across his Fibre Channel network won't be able to utilize the faster network speeds.

"You'd saturate your (server) host bus long before you'd saturate a 1 or 2Gbit connection," he said.

Pilafas said the only way he could take advantage of the faster speeds is if he connected his Hitachi Data Systems (HDS) arrays directly to his Storage Technology tape library. But the company has yet to announce support for 4Gbit/sec. Fibre Channel.

"We're not sure we'll do 4Gbit because really, 10Gbit is so close behind," said Tim Weir, Storage Technology's senior product marketing manager for the Automated Tape Solutions division. "We've got 2Gbit, and we're watching the market. Whatever the market requires, we'll be there. But at this point, it's unclear whether it will be 4(Gbit) or 10(Gbit).

Steve Kenniston, an analyst at the Enterprise Storage Group in Milford, Massachusetts, said the move from 2Gbit/sec. to 4Gbit/sec. Fibre Channel can be compared with the jump from Intel Corp.'s Pentium 3 processors to Pentium 4 processors. The move to 10Gbit/sec. Fibre Channel standard would be a "quantum leap," akin to moving to Intel's Xeon processor.

Hitachi Global Storage Technologies, the disk manufacturing arm of HDS, announced this week that it plans to begin joint testing of new 4Gbit/sec. hard drives with resellers and expects those devices to be available by the summer.

Tony DiCenzo, a member of the Storage Networking Industry Association's board of directors, said low cost and backward compatibility with 2Gbit/sec. and 1Gbit/sec. Fibre Channel will drive sales of hardware offering the new, faster standard.

DiCenzo, who is also director of marketing at Brocade Communications Systems, said that while users won't rush to replace 2Gbit/sec. devices in SANs, the added throughput will be attractive to those expanding an existing infrastructure or grouping switch ports together. "If you can get 4Gbit for the price of 2Gbit, you do it," he said.

Brocade plans to begin testing 4Gbit/sec. and 10Gbit/sec. switches with makers of storage devices in 2005.

Even at $5,000 a port -- compared with $1,000 a port for 4Gbit/sec. Fibre Channel switches -- 10Gbit/sec. Fibre Channel could have a place in a SAN. For example, QLogic's current switch has two 10Gbit ports for interconnections between switches, reducing the number of ports needed for switch clustering. By midyear, it expects to ship 4Gbit/sec. host bus adapters, plus switches supporting that rate as well as 10Gbit/sec.

Some vendors, however, have been cautious about announcing plans for a move to 4Gbit/sec. Fibre Channel.

A spokesman for Cisco Systems said the company has no "immediate plans to support 4Gbit Fibre Channel in our SAN switch portfolio," but added that it would be able to provide support for 4Gbit/sec. Fibre Channel "if strong market demand requires us to do so."