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ISCSI brings VMware to a new audience

Chicken, meet egg: The rising popularity of both iSCSI storage and VMware over the last year means the two technologies are now set to feed off one another in new ways.

Server virtualization software from VMware Inc. might have been a hit in the IT industry for the last four years, but it wasn't until June of 2006, when the EMC Corp. subsidiary released VMware Infrastructure 3 (VI3), that attaching VMware servers to IP SANs was even an option.

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This means that from the low midrange of the market on down, there was an untapped pocket of users who wanted to deploy VMware, but weren't able to afford the Fibre Channel-only shared storage required to make certain features like live data migration work.

Meanwhile, the update to VI3 wasn't the only step necessary to make deploying VMware using IP SANs a reality -- IP SAN vendors also had to test their products with the server virtualization software and become certified with VMware before users would trust the combination, according to IP SAN specialists EqualLogic Corp. and Lefthand Networks Inc. EqualLogic was first certified compatible with VMware in October; Lefthand earned its certification last month.

The other side to this perfect storm has been the rise in iSCSI usage. According to a recent report from IDC, iSCSI is expected to take more than 10% of storage systems revenue and an even greater chunk of the total capacity by 2008. Users are growing more familiar with the lower-cost alternative to Fibre Channel (FC), and according to analysts, on the horizon is a groundswell of new SAN users anxious to use VMware with shared storage. In general they find iSCSI more suited to their experience with Ethernet networks as well as their limited budgets.

"It's still fairly early as far as EqualLogic and Lefthand go," said Steve Norall, analyst with the Taneja Group. "The number of users that have adopted their SANs for use with VMware is still relatively small -- but the combination of VMware and iSCSI has probably just doubled the number of firms they can sell into starting now," a market that in VMware deployments alone Norall hypothesized could reach up to $1 billion over the next year to 18 months.

One EqualLogic user, Arthur Emerson, network administrator for Mount St. Mary College in Newburgh, N.Y., said that before EqualLogic was certified with VMware, his shop struggled along with the more limited features in GSX Server attached directly to storage, while the EqualLogic SAN it had purchased last year was sitting mostly dark.

"We're a small institution where a few of people wear a lot of hats," said Emerson. The college had had VMware GSX deployed for three years, but wanted to move to ESX Server for VMotion live migration capabilities, and also were anxious to try the Consolidated Backup option offered by VI3. In the meantime, FC storage was not an option. "I got a headache trying to just understand [FC]," Emerson said -- and the cost, too, was overwhelming to a shop with 30 virtual machines running on 5 physical hosts and 1.3 TB in storage.

Before VI3 was certified with EqualLogic, Emerson said, data migrations were a pain; automated failover for critical servers wasn't a possibility -- and the company wasn't taking advantage of its SAN storage, either, since most of its servers were virtual machines.

"We had to shut everything down for hardware maintenance [with GSX Server]," he said. "And we had to migrate everything to another physical host by hand." Now, migrating running servers using ESX's VMotion feature with the EqualLogic SAN takes "two mouse clicks," according to Emerson.

It's a story echoed by Colby-Sawyer College, another small institution in northern New Hampshire, and a Lefthand customer. As with Mt. St. Mary College, IT at Colby-Sawyer is managed by an IT generalist with more experience in networking than storage: systems administrator David Blaisdell.

Rather than VMware's groupware product, Blaisdell said, his college was struggling with Microsoft's Virtual Server before Lefthand's certification with VI3 came about. "It gave us pretty good mileage, but we needed a better set of tools," such as a centralized management console and live migration, Blaisdell said. With VMware and shared storage, Blaisdell said he's found the performance of each guest host to be better, and that he can pack more virtual machines onto the same physical hosts.

Blaisdell said Colby-Sawyer is also using Lefthand's Campus SAN option, which splits clusters of Lefthand's Network Storage Modules (NSM) -- commodity servers running Lefthand's software -- into two locations across campus from one another for disaster recovery purposes.

"Because of the combination of VMware's clustering and failover capabilities and Lefthand's clustering features, I have storage, servers and DR all on one [Ethernet] network," Blaisdell said.

A word of caution

Norall said that in general, the combination of iSCSI and VMware will be a boon to users, but cautioned "IT generalist" users to take their time learning about storage, regardless of how experienced they are with the server side and Ethernet already.

"iSCSI is easier to use than Fibre Channel," Norall said. "But there are some operational issues that go along with deploying shared storage in a virtual environment, including and especially capacity planning, that aren't necessarily crystallized in this end user community yet."

Blaisdell acknowledged that "ease of use" does not mean "planning not necessary." For example, he said, he had had to be very careful about naming conventions for the Lefthand clusters storing data for his VMware servers, since Lefthand does failover according to name.

"I had to make sure that cluster names were created in the correct order," Blaisdell said. "And I had to be careful to be consistent about setting how many volume copies to make -- Lefthand has the option of one, two or three."

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