Is there a need for more speed?

Fibre Channel switch and HBA vendors will be shipping 10Gb/s gear in early 2004. The Fibre Channel Industry Association has just backed a 4Gb/s standard, yet how necessary is this when some enterprises have only recently migrated from 1Gb/s to 2Gb/s?

This article can also be found in the Premium Editorial Download: Storage magazine: Storage salary survey: Are you being paid enough?:

Navy wants 40Gb/s--soon
Don't try to tell Hank Dardy that 4Gb/s and 10Gb/s Fibre Channel (FC) constitute overkill. The U.S. Navy's chief scientist for advanced computing says current-generation 2Gb/s FC isn't fast enough to support the advanced visualization applications he's building today. He needs 10Gb/s bandwidth now, and he can see a need for 40Gb/s in the not-too-distant future. He believes the best bet for delivering the low-cost interconnect bandwidth he needs may turn out to be InfiniBand, not FC.

Dardy is heading up a Navy effort, known internally as .Geo, that involves prototyping and building a large visualization infrastructure and applications for the Department of Defense and scientific researchers. Rather than replicating the large image files that feed the visualization application, Dardy's team is building a system that can access them remotely via a distributed file system, then stream them directly over a high-bandwidth WAN.

"We don't have a copy of everything here, but we have active agents out on the network telling us that something of interest is available, and it can be immediately put to use," says Dardy.

Dardy's problem is that the high-definition, TV-quality motion imagery files his group is dealing with are several terabytes each and they easily overwhelm 2Gb/s FC SAN devices. On top of that, users often want multiple visual streams flowing at the same time. So Dardy is pushing vendors for higher-bandwidth alternatives. Without higher-bandwidth SANs, he says, .Geo simply won't fly.

"A doctor, scientist or military officer isn't going to wait on the data," says Dardy. "They'll say, 'The application isn't real-time enough.' We're trying to change the paradigm, which puts a lot of emphasis on data and storage."

Dardy's team has gotten around FC bandwidth limitations by stripping data across multiple Silicon Graphics 2Gb/s SANs and blasting through parallel switches and ports to produce cumulative bandwidth of up to 10Gb/s. The problem, says Dardy, is that it's expensive and complex.

"With 10Gb, we could replace all those boxes with just one and extend the FC out," says Dardy, whose team last year demonstrated a 10Gb/s fiber link running between data centers in Washington, D.C. and Baltimore.

Dardy acknowledges that 10Gb/s FC ports are expected to be several times the cost of 2Gb/s ports. That's why he's pushing for InfiniBand for interconnecting SANs.

"Already, InfiniBand is cheaper than most people think; 4x InfiniBand [about 10Gb/s] ports today are about $1,000, which is competitive with 2Gb FC," Dardy says.

Dardy predicts that InfiniBand will be the best bet for offering affordable SAN fabrics operating well above 10Gb/s. "What we're trying to say to vendors is that 10Gb is just the tip of the iceberg," says Dardy. "We need to go further. I see us needing 40Gb in the 2005 to 2007 time frame."
Henry Ford reportedly told buyers they could purchase his Model A automobiles in any color, as long as it was black. For Fibre Channel (FC) storage area network (SAN) buyers, the situation has been almost as simple: They can buy SAN components such as switches, host bus adapters (HBAs) and storage arrays that operate at any speed, as long as it's 1Gb/s or 2Gb/s.

SAN buyers, however, will soon be faced with more choices when it comes to bandwidth and performance options. FC switch and HBA vendors are expected to begin shipping 10Gb/s SAN gear as early as the first quarter of next year. At the same time, the Fibre Channel Industry Association (FCIA) has backed the idea of a 4Gb/s standard for traffic over the SAN network.

The debut of 4Gb/s HBAs, switches and controllers is expected late next year or early in 2005. Recently, momentum has been building at the FCIA and among some vendors for an 8Gb/s standard. FCIA board member Art Edmonds says an association vote on an 8Gb/s SAN standard will "more than likely" take place.

It begs the question: Will enterprises welcome all the new higher-performance SAN choices? And are storage managers impatient for higher-bandwidth SANs?

In a word, no. Many enterprises have only recently migrated or are in the process of migrating from 1Gb/s to 2Gb/s SANs. Most say their existing applications, OS and server bus architectures are far from consuming all of their SAN bandwidth. While rising storage volumes and the arrival of bandwidth-intensive data types will generate a need for higher-bandwidth SANs, that day is far off.

As a result, most analysts and vendors say that while 4Gb/s SAN gear may find broad application, 10Gb/s ports will be used mainly to speed up inter-switch links (ISLs) between SANs, at least initially.

Need not there yet
"We don't see any bottlenecks today that would require us to upgrade to 4Gb," says Alex Lopez, SAN architect at the University of California Davis Medical Center. Lopez, who runs two SANs containing a total of 24TB of data, migrated to 2Gb/s ports nine months ago as part of a larger SAN and server upgrade. The servers, which use PCI, don't come close to using up all of the SAN's bandwidth. "So, unless we add a supercomputer or multiple video applications, we won't have a need for 4-gig or 10-gig SANs for a long time," says Lopez.

Mark Deck, director of infrastructure technology at National Medical Health Card Systems Inc., feels the same way. The prescription drug program management company is currently upgrading its Hewlett-Packard Co. (HP) N-class servers to faster K-class machines and its HP XP256 SAN from 1Gb/s to 2Gb/s to keep up with online transactions. But he says that even the new servers won't fully take advantage of the increased SAN bandwidth.

Even vendors backing higher-bandwidth SANs say most enterprises aren't clamoring for them yet. While HBA vendor Emulex, for example, expects sales of its highest-performance dual channel 2Gb/s HBAs to double this year, "it would be overstating it to say that there's a strong pull for 4-gig SANs," says Mike Smith, the company's executive VP of worldwide marketing.

Many SAN switch vendors agree. "At this point, 4Gb/s appears to be a technology in search of a solution," says Jim Miller, senior product marketing manager at McData Corp., which plans to support the 10Gb/s standard for ISLs in the first half of 2004, followed in about nine months by 4Gb/s if there's demand. "But," Miller adds, "we see nothing on the horizon, even tape SANs, that will be able to drive that [4Gb/s]."

Gearing up for 4Gb/s
Why the vendor push for higher-bandwidth SAN products--4Gb/s, specifically--even in the face of apparent enterprise-user indifference? First, intense competitive pressures are prompting vendors to attempt to get a leg up on rivals by pushing for 4Gb/s SANs. QLogic Corp., for example, aggressively pushed for the FCIA vote in favor of 4Gb/s FC and expects to have HBAs for evaluation early next year, well ahead of rivals. Although QLogic marketing VP Frank Berry acknowledges there's little demand for 4Gb/s FC SANs, he says that there eventually will be.

QLogic's strong pro-4Gb/s stand has forced competitors to consider supporting the standard or risk the appearance of falling behind. "A year ago, I'd have said Fibre would move directly from 2Gb to 10Gb, but today that's not so clear," says Emulex's Smith. "I've got to be ready to do both, then wait and see which camp is going to blink."

"With 1GB iSCSI becoming widely available in 2004, the low end of the market will move in that direction, so FC vendors need a growth path they can offer higher-end customers," says Phil Brotherton, VP of marketing at HBA maker JNI Corp., which expects to ship a 4Gb/s device in the second half of next year. "Competition from other technologies is definitely a factor driving the proliferation of higher-bandwidth FC options."

The third reason for the emergence of the 4Gb/s Fibre standard: It's becoming clear to some vendors that 10Gb/s FC will be expensive and difficult to deploy. Rather than fight an uphill battle by attempting to sell a 2Gb/s-to-10Gb/s SAN migration, many vendors are proposing an easier interim alternative with 4Gb/s.

The high cost of 10Gb/s
"Ten-gigabit is going to be a disruptive beast and one that is going to be incredibly costly," says storage analyst Arun Taneja of the Taneja Group, Hopkinton, MA. "In fact, based on the cost differential we see between Gigabit Ethernet and 10GbE, 10Gb Fibre could end up being at least five times more costly than 2Gb Fibre."

And that estimate could be optimistic. Ed Chapman, senior director of product management at Cisco, believes that initially, the cumulative cost difference between 2Gb/s and 10Gb/s SAN infrastructure--HBAs, switches, directors, drives and cabling--will be closer to 10-to-one. The higher cost of optical devices needed to drive 10Gb/s FC traffic is a major factor. Based on today's prices, optics for a 10Gb/s FC SAN would cost about $2,000, compared with the current price of $80 for the optics used in 1Gb/s and 2Gb/s FC SANs, according to Peter Wong, manager of strategic marketing at networked storage component manufacturer PMC-Sierra, in Santa Clara, CA.

"Originally, the thinking was that 10Gb Ethernet would drive up volumes and quickly drive down the cost of 10Gb fiber optics and other components, but that hasn't happened," says Wong. "The volumes for 10GbE haven't been there."

As a result, says Wong, PMC-Sierra expects 10Gb/s prices to fall slowly and in the near term, he sees a small market for 10Gb/s FC products. The company has scaled back the level of its investments in 10Gb/s FC components, shifting its emphasis to 4Gb/s products.

But it's not just the cost of 10Gb/s Fibre ports that will pose a barrier to the technology's wide deployment within SANs. Incompatibilities between 10Gb/s and existing 1Gb/s and 2Gb/s SAN infrastructure will also hinder migration, experts say. For one thing, most switch and HBA vendors say it won't be practical to work 10Gb/s Fibre elements into the existing auto-sensing scheme that today lets switches detect whether they are connected to 1Gb/s or 2Gb/s HBAs and disk arrays, and then adjust accordingly. As a result, it may not be easy to mix 10Gb/s-capable gear into existing SANs.

Also, it's expected that 10Gb/s SAN equipment won't be able to use the multimode fiber cabling currently tying together most SANs.

"All of that would have to be replaced with more expensive nine-micron single-mode fiber cabling," says Scott Drummond, program director for storage networking at IBM. "All of those things mean a migration to 10Gb would take more planning and be more expensive than what enterprises saw moving from one to 2Gb."

As a result of the high cost and the compatibility issues surrounding 10Gb/s Fibre, many vendors and analysts now believe it will not be deployed soon as a mainstream replacement for 2Gb/s Fibre linking servers, switches and storage arrays. Instead, say vendors and analysts, 10Gb/s Fibre will make the most sense as a backbone technology, speeding up ISLs for applications such as SAN consolidation and remote backup and data movement. Using 10Gb/s for ISLs could also cut complexity and cost, compared with the current practice of trunking together multiple 2Gb/s links, experts say.

"Speeding up [inter-switch links] is where you'll see the real use of 10Gb Fibre in the beginning," says IBM's Drummond. "We're seeing larger and larger SANs, some with 1,000 ports. That will drive the need for higher-speed ISLs in the near future."

Today, enterprises can use SAN extension routers from vendors such as Computer Network Technology (CNT), LightSand and Nortel Networks to merge multiple SAN fabrics and connect them over wide-area Sonet networks. Using technologies such as dense wavelength division multiplexing has allowed vendors to squeeze more bandwidth out of WAN connections such as Sonet. Feeding those fast WAN connections with 10Gb/s Fibre rather than 2Gb/s would mean more efficient use of expensive Sonet bandwidth. "For ISLs, 10Gb means simplicity," says Drummond. "It means fewer boxes and less money."

Still, vendors acknowledge that only their largest customers are experiencing bottlenecks while using 2Gb/s Fibre connections to feed ISLs. (See "Navy want 40Gb/s soon")

Enter 8Gb/s SANs
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

Dig deeper on SAN switch

Pro+

Features

Enjoy the benefits of Pro+ membership, learn more and join.

0 comments

Oldest 

Forgot Password?

No problem! Submit your e-mail address below. We'll send you an email containing your password.

Your password has been sent to:

-ADS BY GOOGLE

SearchSolidStateStorage

SearchVirtualStorage

SearchCloudStorage

SearchDisasterRecovery

SearchDataBackup

Close