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University learns storage lesson

Seattle Pacific University switched from a FC to an iSCSI SAN and discovered that FC does not necessarily out perform iSCSI -- but still costs more.

A Fibre Channel (FC) SAN was the best storage option when Seattle Pacific University (SPU) chose it four years ago. Upgrade time rolled around this year, however, and SPU systems analyst Joel Swanson, discovered that FC could be outclassed by IP SAN technology that lowered costs and eased management problems.

SPU, a college with about 3,600 undergraduates, first implemented a 2 terabyte (TB) FC SAN as the storage backbone for Microsoft Exchange. Those 2 TBs seemed huge back then, but it's been dwarfed by e-mail volume, as e-mail has become a core business application.

"When we deployed our Exchange infrastructure with our first SAN, 30 MBs of disk space per person was plenty," Swanson said. "Nowadays, people have a history of three to four years of e-mail in storage, and they're using e-mail more and more."

Lacking large enough e-mail storage space, SPU's staff and faculty engaged in some questionable practices, the university said. They were deleting e-mails that should have been saved for retention for information critical to research and legal requirements. Also, people were creating personal e-mail files on their desktops, files that got lost when a desktop hard drive crashed.

More disk space would make it possible for everyone to have a primary file location on the central server, as opposed to the desktop. More disk space would also make it easier to manage Exchange. "We didn't even have enough extra disk space to do defragmentation," Swanson said.

The easy path would have been to upgrade the FC SAN. "We already had it in place and were familiar with it," Swanson said. "We could have stuck with our vendor and added disk space."

A little research into iSCSI convinced Swanson that the easy choice might not be the best choice. FC costs seemed exorbitant when compared to iSCSI. For example, FC required $1,000 interface cards for each server.

"When you're only spending about $3,000 for a server, it's prohibitive to add a $1,000 card just to talk to your disk space," Swanson said. By comparison, iSCSI would only need network interface cards that cost $100 each. The university found that connecting a server to the FC SAN cost more than buying extra disk space for that server.

Just upgrading the current SAN wouldn't yield performance increases either, Swanson said. Typically, upgrading a FC SAN means just increasing disk capacity and not overall infrastructure speed. "You're just adding more disks to the same number of processors and the same amount of throughput," he explained.

Swanson evaluated iSCSI products from LeftHand Networks Inc, Dell Corp., EMC Corp. and Network Appliance Inc. (NetApp) LeftHand got his team's nod for its product capabilities and prices, early adoption of iSCSI, track record and close ties to Microsoft. EMC and Dell had just introduced iSCSI products then, and those products and NetApp's were more expensive than IP SAN technology from LeftHand, Swanson said.

In particular, the rejected products charged extra for functionality modules, such as snapshotting. "LeftHand gives you the whole software package. For example, you get unlimited snapshots without any extra cost, and you wouldn't want to get iSCSI without getting that functionality," Swanson said. "NetApp knows that, and they are charging more for it."

A typical LeftHand package contains the company's SAN/iQ Distributed Storage Matrix SAN software and Network Storage Module hardware. Pricing starts at about $20,000.

Microsoft iSCSI Initiator 2.0

Microsoft's iSCSI Initiator 2.0 software helped SPU's IT staff cruise through and add functionality during the deployment of eight LeftHand NSM 150 appliances. Initiator 2.0 brings integrated multipathing functionality and x64 capabilities support to NSM 150s."Within a few minutes of being shown how to use it, we were up and running," Swanson said.

LeftHand's system enabled comparatively inexpensive connection of many servers.

Four physical servers, each a two-node cluster, are connected to the LeftHand system. One of the two-node clusters acts as an active/passive Exchange 2003 server. The other one is an active/active file server. Both clusters run on the Windows 2003 server platform. The Exchange environment is supporting about 800 to 1,100 active users at any given time.

Swanson found that scaling up wouldn't break the budget, either. "With iSCSI, you can increase your capacity at very small intervals," Swanson said. "You don't have to make it a major capitol expense every time you need to upgrade performance."

If Swanson had relied on hearsay, then throughput capabilities could have been an iSCSI deal breaker. "A lot of people say that the throughput of Ethernet is not as high as that of FC," he said. He discovered, however, that iSCSI enabled multiple throughputs to each device, providing comparable results.

In fact, with the FC SAN, SPU users were getting a whole lot of "wait states", wherein Outlook was trying to contact the Exchange server. That's not happening with iSCSI.

Simplified administration

After deployment, Swanson found that LeftHand's SAN iQ software enabled easier administration than the FC SAN. "With the SAN, it's pretty cryptic to go in and use different commands and different screens with a keyboard," said Swanson. "You have to know the interface very well." LeftHand's interface is more intuitive and looks like a Windows' environment with menus and right clicking options, he said.

Swanson advises other IT directors to ignore the "common wisdom" that FC performance blows away iSCSI. He's found that to be false. "In our experience, iSCSI is faster and easier to manage and upgrade." As for expense, when the numbers were crunched, Swanson found that upgrading the FC SAN would have cost three times more than the switch to iSCSI.

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