Invasion of the iSCSI SANs

As the technology has matured, IP-based storage arrays have established a beachhead as the preferred low-end SAN option.

News Story by Robert L. Mitchell

When Jim Tarala oversaw the rebuilding of his firm's network and IT infrastructure last year, he never dreamed he'd throw out his Fibre Channel SAN in favor of IP-based networked storage. The savings, however, were just too large to ignore.

Tarala, CIO and chief technology officer at Schenck Business Solutions, a 500-partner accounting firm in Milwaukee, was comfortable with his EMC Clariion storage system, but it was running out of space. Tarala also wanted to eliminate direct-attached storage on his mySQL and Microsoft Exchange Server systems in favor of networked storage. He decided to replace the entire system but initially dismissed the idea of using IP storage-area networks (SAN)-systems that use the iSCSI protocol to allow servers to access stored data over an IP network-rather than direct-attached or Fibre Channel arrays. "I wasn't comfortable with the overall architecture," Tarala says.

Then he discovered that replacing the aging FC700 with a 1.5TB system would cost more than US$90,000, while a 2.5TB iSCSI-based PS Series system from EqualLogic in, would cost just US$47,000. Schenck gave Fibre Channel the boot. Tarala now has three PS Series systems with more than 7TB of capacity that support 12 servers.

"I spent half of what I budgeted, doubled my capacity, and it performed flawlessly," he says.

More than two years after the iSCSI protocol was ratified as an Internet Engineering Task Force standard, early adopters say IP SANs are not only ready for production deployments but also offer an alternative to Fibre Channel for low-end and midrange storage. Performance and reliability of iSCSI arrays have improved, and iSCSI SANs are significantly less expensive to set up and manage than Fibre Channel SANs, users say.

The high costs of traditional SANs have restricted the technology to mostly first- and second-tier data center applications. Now storage administrators are setting their sights on iSCSI as an alternative for some second-tier applications.

And a second wave of storage consolidations is already under way: Administrators are replacing direct-attached storage used in departmental servers with local, iSCSI SANs. Robert Gray, an analyst at IDC, says the strongest growth is coming from large companies, which have huge numbers of departmental servers that can benefit from consolidating storage.

Early misgivings about iSCSI's capabilities have faded. Tarala was wary of the performance and reliability of the Serial ATA (SATA) drives used in EqualLogic's system but says the new SAN's performance has been comparable to the system he retired.

The new storage system is also more efficient to run. Because the SAN is IP-based, Tarala's Windows server administrators can manage it.

"You don't have to wait to bring in an outside technician to check that the [Clariion] tuned the array," he says. And moving from direct-attached to networked storage has improved staff productivity. "Everything boots from the SAN, and they can bring up a new Windows 2003 server in 20 minutes," Tarala says.

Until recently, the major SAN vendors were reluctant to release iSCSI products, citing maturity issues and server CPU performance bottlenecks that might arise in processing traffic associated with iSCSI and the chatty TCP/IP protocol. But thanks in part to faster processors, that bottleneck never materialised for Tier 2 applications.

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