iSCSI SAN performance remains strong after 10 years

Despite early doubters, iSCSI SAN performance remains strong after 10 years and continues to gain ground on Fibre Channel as a storage protocol.

This year marks the 10th anniversary of iSCSI storage-area networks (SANs). After early doubts that iSCSI could be a viable contender to Fibre Channel (FC), the Ethernet storage protocol has established a loyal base among small- to medium-sized businesses (SMBs). The adoption of 10 Gigabit Ethernet (10 GbE) and enhancements to Ethernet storage can bring iSCSI a brighter future in larger organizations as well.

The early concerns iSCSI faced included whether Ethernet could be a legitimate storage protocol and if the larger FC-centric storage vendors would embrace it. Although a handful of early startups failed, EqualLogic and LeftHand Networks gained enough of a customer base to attract large suitors. Dell Inc. finalized its acquisition of EqualLogic for $1.4 billion in 2008 and quickly became the iSCSI market leader, and Hewlett-Packard (HP) Co. bought LeftHand for $360 million later that year to join the iSCSI SAN arena. All the other major storage vendors include iSCSI in multiprotocol arrays or iSCSI-only systems.

The emergence of 10 GigE also makes iSCSI SAN performance more competitive with FC, which is moving from 8 Gbps to 16 Gbps but requires more expensive switches and adapters. The Data Center Bridging (DCB) standard, finalized in 2011 by the Internet Engineering Task Force (IETF), also makes iSCSI a stronger storage play because it mitigates packet loss as data is sent through a pipe. Making Ethernet less lossy makes it behave more like FC.

Analysts anticipate the iSCSI protocol will keep its hold among SMB customers and has a chance to encroach further into the enterprise for less mission-critical applications in departments and branch offices. While FC remains the dominant storage protocol, iSCSI should continue to grow.

iSCSI has expanded from $18 million in revenue in 2003 to $3 billion in 2011, according to Framingham, Mass.-based market research firm IDC. That gave it approximately 15% of the networked storage market share and 20% of the block storage share last year.

“At 10 GigE and with enhancements to Ethernet, iSCSI can go into higher areas -- but not in the most mission-critical applications,” said Arun Taneja, founder and consulting analyst at Taneja Group in Hopkinton, Mass. “IT guys are telling me they're not ready to let Fibre Channel go away. They're rapidly moving from 8-gig to 16-gig Fibre Channel. The iSCSI evolution I'm seeing is that it will move further into the enterprise with 10 GigE and it can take over some lower-end Fibre Channel applications. Many department applications don’t need Fibre Channel.”

Ten years ago, iSCSI vendors went after customers who didn’t have SANs and didn’t want to pay for FC gear and expertise. Many found there was less of a tradeoff in performance than expected.

“People traditionally in Fibre Channel are considering iSCSI because it’s a simple, affordable solution,” said Dale Degen, a manager of HP’s LeftHand storage. “I think with the adoption of 10 GigE, you will see iSCSI in the data center.”

Server virtualization is another big driver for iSCSI. Because many advanced features of server virtualization require networked storage, organizations look to add SANs that are cheaper and easier to manage when they begin virtualizing servers.

Laz Vekiarides, an executive director at Dell EqualLogic, said approximately 75% of EqualLogic SANs are deployed in some server virtualization environments. “There's a new class of customer in larger enterprises that never would have bought a SAN before,” he said.

iSCSI: Cheaper and less complicated than FC

Granger Community Church, based near South Bend, Ind., installed its first iSCSI SAN in 2006 from EqualLogic (before it was acquired by Dell). Fibre Channel was “too complicated” to consider, said Jason Powell, director of IT at the church. Granger uses EqualLogic PS100E and PS6000E arrays, running six physical servers and about 40 virtual machines.

“In the six years we've used it, we've had no performance issues with it,” Powell said. “Back then, people were saying iSCSI would have a performance problem. We were hearing that iSCSI wouldn't amount to anything. Today, Fibre Channel isn't even on our radar.”

Hobart Brothers, a Troy, Ohio-based welding manufacturer, has a LeftHand P4500 G2 with 10 TB of usable capacity and six older LeftHand NSM 160s with 4.1 TB of usable capacity for archived data. The two-chassis P4500 G2 supports 28 virtual machines for Microsoft Exchange, SharePoint, SQL Server and individual user files.

Gaston Brown, systems administrator at Hobart Brothers, said he considered FC too expensive and iSCSI worked fine.

“We checked into Fibre Channel but we couldn't justify the cost,” Brown said. “We would have had to pay $8,000 to $12,000 for a Fibre Channel SAN with less storage than the iSCSI SAN. We haven’t had any [iSCSI] performance or reliability issues. I’ve had no downtime.”

Donald Wilkins, IT director at health care transaction clearinghouse Navicure Inc. in Duluth, Ga., agreed that FC is unnecessary for his needs because his EqualLogic iSCSI SANs are holding up fine running his Oracle database.

“We're hammering the SAN all day long and it’s performing well,” Wilkins said. “Have we thought about Fibre Channel? Yes. Have we wanted to do that? No, we think iSCSI is sufficient for our needs. The simplicity of managing an iSCSI SAN is a lot easier than dealing with Fibre Channel. And 10 GigE is adequate for our needs.”

Navicure purchased its first EqualLogic PS100 iSCSI SAN in 2004 and has since added 34 arrays that include the PS1200, PS3600, PS5000, PS6000 and PS6510. Wilkins said approximately 30% of his network runs on 10 GbE, with the rest on GigE.

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Christopher Patti, director of technology at AccuWeather Inc., said his firm purchased two PS5000 arrays in 2008, months after Dell acquired EqualLogic. The State College, Pa.-based weather forecasting service has acquired four more EqualLogic arrays and has around 50 TB of usable storage on its iSCSI SANs.

AccuWeather consolidated onto EqualLogic from EMC Clariion and HP EVA Fibre Channel arrays and NAS systems that had been purchased for individual projects. The company now has PS5000XV SAS and PS5000E and PS6000E SATA arrays for its VMware and SQL Server clusters and to support its website. AccuWeather runs SQL Server on SAS arrays and virtual machines and lower-performance applications on SATA.

Patti said his team found it easier to manage and allocate storage on EqualLogic. “Our storage administrator is also our VMware administrator,” he said. “He’s a jack of all trades. We needed to be able to get our storage up and running quickly.”

Patti said the switch to EqualLogic from FC SANs saved money both in upfront costs and service and maintenance. He said the original EqualLogic installation took less than an hour and major upgrades can be performed in a day without using outside consultants.

“Trying to upgrade a Clariion required an expert to come out and get FLARE [Clariion’s operating system] upgraded,” he said. “People here were afraid of it. SANs are a great piece of technology, but people are scared to heck of them. We can’t have downtime. We’re giving weather forecasts to customers worldwide. We can’t say we’ll go offline, say on Saturday. We’re not a nine-to-five operation.”

Patti said uptime is more important than high performance for AccuWeather’s storage. The weather service stores a great deal of satellite data required for its forecasts. The data is crucial for short periods of time before it's replaced by more recent information.

“Most of our data doesn’t matter once it’s more than an hour old,” he said. “We have a high uptime requirement. We have a lot of radar data, but it’s valid for about 15 minutes.”

As for performance, he said iSCSI is good enough for his needs.

“Eight-gig Fibre Channel was way more throughput than we needed,” Patti said. “Now we have 1-gig throughput, but we bind four channels for 4-gig performance.”

iSCSI SANs take on advanced features

In a decade, iSCSI SANs have acquired some higher-end capabilities. HP includes its new Peer Motion federated storage feature in LeftHand and in its higher-end 3PAR platform. Peer Motion lets customers move active volumes dynamically between arrays.

Christchurch, New Zealand-based infrastructure hosting provider vBridge uses Peer Motion to move data between LeftHand arrays in three data centers to scale storage and move data without downtime.

“If a customer wants to move from one service or site to another, we can move the storage nodes with no downtime,” said Hamish Roy, vBridge's director. “We can move LUNs from one cluster to another using the same management group of maintenance on nodes. It ensures no application downtime.”

Roy said vBridge can manage its storage efficiently without paying for FC or even 10 GigE for its SAN.

“We’re making do with 1-gig very well now. The way LeftHand scales provides us with extra throughput every time we add a node,” he said. “Fibre Channel introduced some price problems, and we worried about how it would scale. We would hit a point where performance would hit a ceiling. With LeftHand, we can keep scaling [iSCSI SAN] performance much further.”

Overall, vBridge has 24 LeftHand nodes -- a mixture of P4500 and P4300 -- for approximately 120 TB of usable capacity. Roy said about half that capacity is being used. The provider has used LeftHand since it started offering services in 2010.

“We’ve had zero downtime -- planned or unplanned -- as far as our storage goes,” Roy said.

Senior news director Dave Raffo contributed to this story

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