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

The faster 4Gbit/sec. standard was approved in June by the Fibre Channel Industry Association, but vendors waited to develop the technology because of a slumping market. Now, makers of Fibre Channel host bus adapters (HBA), switches and disk drives say that devices adhering to the new standard are on the horizon and will cost roughly the same as or a little more than 2Gbit/sec. hardware.

Some vendors are also looking to release products with 10Gbit/sec. capabilities. But some IT managers this week said they may not be able to benefit from the Fibre Channel performance boosts at this point because of server and tape drive I/O bottlenecks.

Gary Pilafas, senior storage and systems architect at UAL Loyalty Services Inc. in Arlington Heights, Ill., said that even if 4Gbit/sec. products cost no more than his existing ones, he's wary about installing them on his SAN. The application servers that the United Air Lines Inc. subsidiary backs up across its Fibre Channel network couldn't take advantage of the faster network speeds, said Pilafas.

"You'd saturate your (server) host bus long before you'd saturate a 1- or 2Gbit connection," Pilafas said. UAL could use the speedier throughput only if he connected its Hitachi Data Systems Corp. disk arrays directly to its Storage Technology Corp. tape library, he added. But StorageTek has yet to announce support for 4Gbit/sec. Fibre Channel.

Another IT manager, who works at a large Midwestern insurance company and asked not to be identified, also said that replacing 2Gbit/sec. Fibre Channel equipment with 4Gbit/sec. devices isn't an attractive option now. "If a tape drive can only produce 20MB/sec. throughput, doubling the speed of the Fibre Channel port the tape drive is connected to doesn't increase the throughput," he said.

Steve Kenniston, an analyst at Enterprise Storage Group Inc. in Milford, Mass., said the move from 2Gbit/sec. Fibre Channel to 4Gbit/sec. is comparable to the jump from Intel Corp.'s Pentium III processors to the Pentium 4 line. Migrating to 10Gbit/sec. products would be "a quantum leap" for users, he added.

San Jose-based Hitachi Global Storage Technologies Inc. this month announced plans to begin joint testing of 4Gbit/sec. disk drives with storage vendors and added that it expects those devices to be generally available by 2005.

Vendors such as Brocade Communications Systems Inc. and McData Corp. have said they plan to offer devices supporting the faster speeds later this year or in 2005. However, some companies remain cautious about supporting the new technology.

For example, a spokesman for Cisco Systems Inc. said it has no immediate plans to support 4Gbit Fibre Channel in its SAN switch portfolio. He added that Cisco could add 4Gbit/sec. capabilities "if strong market demand requires us to do so."