Sizing Up Speed

Industry debates the future of 10G-bps fibre channel.

They say that New York is the city that never sleeps—and neither does its data processing. From a Lower Manhattan data center, NYCAPS, the New York City Automated Personnel System, handles 18 terabytes of data for municipal human resources needs. The SAN runs on Hitachi Ltd. Lightning 9900V and Sun Microsystems Inc. T3 arrays.

The mystery, Computer Systems Manager Rodrick Brown said, is to know how well the data flows through NYCAPS 2-gigabit-per-second QLogic Corp. Fibre Channel infrastructure.

"We dont have any tools to monitor it. Thats something that weve been trying to push for," Brown said. So when vendors talk about future storage systems running at twice or even five times current speeds, he questions the usefulness. "Thats something we would look into," he said.

But all networks eventually get faster, and for now, the debate centers on just how much faster and when. The networking industry already runs 10 Gigabit Ethernet products, while todays Fibre Channel runs at just 1G bps or 2G bps. Fibre Channel must catch up, or vendors pushing storage over IP will have an advantage, industry watchers say.

The case for 4G-bps Fibre Channel centers on convenience and price, said Rob Davis, vice president of advanced technology for host bus adapter and switch maker QLogic. "First of all, 10 gigabit is not backward-compatible to 1 and 2 gigabit. Secondly, the cost for 10 gigabit, we think, is going to be fairly prohibitive to the mass market for the next few years," said Davis, in Aliso Viejo, Calif.

Hard drive vendors are definitely moving to 4G bps, Davis said, so QLogic has to build the technology anyway. And 4G bps, using existing cable, can traverse 100 meters, whereas 10G bps can go only 20, he said.

Davis acknowledged that 4G bps backward compatibility applies only to wire connections, not to actual port slots. So while Fibre Channel can interoperate with a 4G-bps port on one end and a 1G-bps or 2G-bps port on the other, the 4G-bps adapter still requires an upgraded physical slot to sit in, which means users will need to buy new switches or upgraded storage, he said.

Officials at Emulex Corp., another major host bus adapter vendor, said the thinking of 4G-bps advocates is flawed. Theres nothing specifically wrong with 4G bps, but its an example of building needless technology because its possible, said officials, in Costa Mesa, Calif. The 10G-bps speeds wont cost too much more, and because interswitch links and server and storage slots are finite, users will want to maximize them, officials said. Tape backups and restores can easily saturate existing 2G-bps connections, they said.

For customers making a buying decision, the bandwidth issue may wind up as a high-tech popularity contest. Most storage companies and major switch vendors, such as Hitachi Ltd. and IBM, the duo of Brocade Communications Systems Inc. and McData Corp., and SAN newcomer Cisco Systems Inc., say that 10G bps is the next step.

EMC Corp. officials said its too soon to take a side, but even at Computer Network Technology Corp.s Inrange division, which specializes in the vertical markets that would need the faster networks the soonest, officials said 10G bps is the next stop on their road map.

But there is a twist, said Brian Mason, director of storage engineering at network testing specialist Spirent plc. "Just that fact that youre trying to make [4G bps] interoperable might present more technical challenges than 10 gigabit," said Mason, in Rockville, Md. "Realistically, the transition from [1G bps] to [2G bps] went fairly smoothly," but where 10G bps had an Ethernet parallel for testers to compare, 4G bps is starting from scratch, he said. So the technologies might arrive to market at the same time, he said.