Is there a need for more speed?


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Enter 8Gb/s SANs

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Now that 4Gb/s Fibre Channel (FC) storage area networks ( SANs) are gaining momentum, can 8Gb/s be far behind? That's a question SAN vendors and officials at the Fibre Channel Industry Association (FCIA) say is now being actively discussed, and an FCIA vote is likely, according to board member Art Edmonds.

"The question now with eight, like it was with 4Gb, is should it be an interface speed at the disk drive level only, or should it be brought out onto the storage network?" says Edmonds. "That is still in discussion."

The big question, according to Edmonds and other experts, is whether 8Gb/s Fibre devices could be made to interoperate with existing 1Gb/s and 2Gb/s SANs. Specifically, would 8Gb/s devices be able to work with existing cabling and auto-sensing systems? That type of interoperability is one big advantage of the anticipated 4Gb/s SANs, and the lack of it is one of the issues expected to complicate 10Gb/s SAN deployments.

If 8Gb/s SAN components can be made to interoperate with existing fabrics, predicts Rick Villars, VP of storage systems for IDC, enterprise storage managers will eventually see them on the market.

"Many of the same issues driving 4Gb/s SANs will eventually drive 8Gb/s SANs," he says.

Storage managers such as National Medical Health Card Systems' Deck, who's using IP over a T3 line to mirror his company's Oracle database at a backup data center in Little Rock, AR, say that moving to 10Gb/s would be overkill.

Certainly, 4Gb/s Fibre technology will bypass many of the cost and complexity problems lurking around the 10Gb/s standard. For example, 4Gb/s HBAs and switches are expected to be compatible with the existing auto-sensing schemes used for 1Gb/s and 2Gb/s Fibre. And devices with 4Gb/s Fibre ports are expected to use existing multimode cabling, although maximum cable distances at 4Gb/s will drop to about 125 meters from the 300 meters that is possible with 2Gb/s Fibre.

In the end, say analysts and storage managers, the pace with which enterprises and vendors embrace 4Gb/s Fibre SANs will depend on the cost. More specifically, how much will 4Gb/s SAN gear cost, vs. existing 2Gb/s SAN equipment? If 4Gb/s SAN gear carries only a small premium, or no premium, over 2Gb/s equipment, enterprises will choose it whether they need the bandwidth now or not. That thinking is what's fueled the migration during the last year from 1Gb/s to 2Gb/s SANs, says Taneja.

"If you look at the 1Gb to 2Gb transition, many of us were saying the same thing that's being said now: 'Enterprises don't need it,'" recalls Taneja. "People went to 2Gb not because they needed it, but because the vendors of chips and other FC equipment made 2Gb essentially the same cost as 1Gb."

Vendors, however, disagree about whether 4Gb/s SAN gear will cost more, and if so, how much more.

QLogic's Berry predicts 4Gb/s SAN ports and other equipment will be "about the same price as 2Gb."

But Bill Mottram, director of strategic alliances at HP, believes 4Gb/s SAN equipment will carry a 10% to 20% price premium over 2Gb/s gear for at least the first six months after it becomes available late next year or early in 2005. Other vendors and industry analysts predict that 4Gb/s gear will initially command a price premium of up to 25% over 2Gb/s equipment and that some 4Gb/s price premiums will exist for up to two years.

The wild card is the future pricing of 2Gb/s Fibre ports and HBAs. If manufacturers continue to offer 2Gb/s gear even after 4Gb/s equipment arrives, 2Gb/s equipment prices could drop to levels comparable to Ethernet port prices. That would not only mean bargains for users, it would also mean plenty of lower-cost competition for new, expensive 4Gb/s gear.

And that's just what some experts expect. "In the one- to 2Gb transition, manufacturers closed off 1Gb fairly quickly after two arrived, because they didn't want the cost of carrying two test beds," says IBM's Drummond. "But 4Gb will be a tougher sell, so they may be forced to continue offering 2Gb HBAs for quite a while. And the cost of that stuff should come down quickly."

In fact, Emulex's Smith says his company will continue offering 2Gb/s HBAs as long as customers want them. And one competitor has already indicated it plans to use low 2Gb/s pricing to gain market share. JNI Corp. is rolling out a 2Gb/s dual-port HBA targeted at Windows servers and priced at $600 per port, about 45% lower than current 2Gb/s port prices.

Hedging their 4Gb/s bets
Given the uncertainty over 4Gb/s pricing and enterprise migration rates, it's not surprising that many vendors--mainly switch and systems makers--are hedging on when they'll make 4Gb/s products available. Neither Brocade Communications Inc. nor Nortel are committing to a date for shipping 4Gb/s products. Jack Hunt, director of storage marketing for Nortel, says, "The jury's still out on whether there will be a mass deployment of 4Gb Fibre. If that happens, we'll be ready to support it."

Similarly, officials at Brocade say the company is waiting for demand for 4Gb/s Fibre to materialize from its OEM customers before committing to a specific date for supporting 4Gb/s ports. HP say it's only recently begun to evaluate whether to support 4Gb/s SANs.

While officials at EMC say the company will support 4Gb/s if demand develops, they express doubts that it will happen. "A lot of [customers] have said they'll move directly from 2Gb to 10," says Paul Ross, EMC's director of storage networks marketing. "We don't know if 4Gb will become widely interesting to enterprises. Right now, there are just a couple of vendors pushing for it."

But analysts predict that even reluctant storage vendors will warm to 4Gb/s SANs, particularly if prices for the high-bandwidth products fall quickly, coming close to current 2Gb/s levels. "That's likely," says Rick Villars, VP of storage systems at IDC. "That's why there's a drumbeat of the inevitable right now around 4Gb."

What should enterprise storage customers do as that drumbeat becomes louder? First, understand that 10Gb/s Fibre initially won't be practical as a widespread replacement for 2Gb/s products, but it will be useful to speed up ISLs. Consider whether your SAN topology could benefit from such a high-speed backbone boost.

When 4Gb/s Fibre ports and other elements do become available, consider waiting at least six months before migrating. Given intense competition among HBA and switch vendors, analysts expect 4Gb/s prices to drop quickly.

And third, keep an eye out for bargains on 2Gb/s Fibre gear. If 2Gb/s SAN fabrics provide adequate performance for your applications, you could be in line for some savings.

For their part, storage managers agree that if 4Gb/s prices fall quickly, there's no reason they won't embrace the higher bandwidth. "We may not need it today, but in a year or two, who can say?" says National Medical Health Card Systems' Deck. "It's better to get caught with too much bandwidth than too little."

This was first published in December 2003

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