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Storage administrators tackle block virtualization

At Storage Decisions, users struggled with the question of where storage virtualization should take place: in a switch, an appliance or the storage array itself.

Storage virtualization poses more options and demands more decisions from administrators than VMware-dominated server virtualization, and this week storage administrators spent a lot of time at Storage Decisions discussing the pros and cons of those options.

One thing nearly everyone agrees on: Storage virtualization can benefit practically every company with networked storage. It's how to get there that brings difference of opinions.

Storage virtualization information
What is storage virtualization? 

Hitachi TagmaStore to scale even higher

Thin provisioning pros and cons

As laid out by analyst Mark Staimer of Dragon Slayer Consulting at a Storage Decisions session, storage virtualization methods include unified SAN-NAS systems, file-based NAS virtualization and block-based SAN virtualization. Block-based virtualization received the most attention from users at the show, which leads to another question: Should the virtualization take place in a switch, in an appliance or the storage array?

Matthew Yotko, director of technology infrastructure at the Barry Diller-owned conglomerate IAC in New York, uses 3PAR's thin provisioning to virtualize storage in his arrays and VMware on his servers. Yotko rebuilt IAC's infrastructure when he was hired there in 2005, and estimates he saved "a couple million dollars" by going with a virtualized platform. IAC has dual active-active data centers in New York and Los Angeles and does asynchronous replication between 3PAR InServ storage servers at each location.

"Our SAN is so modular now, if I need more infrastructure, I simply add more infrastructure," Yotko said. "If I need more disk, I go and buy more disk. It stripes in about a day, and I can start using the new storage immediately."

Thin provisioning let IAC buy 50 percent less disk up front and also improves application performance, according to Yotko. "Each application uses all the spindles," he said. "It goes where you need it when you need it."

Paul Ferraro, storage manager of telecom chip maker Qualcomm, also uses 3PAR's thin provisioning with VMware, but hasn't jumped in with both feet. He uses 3PAR to virtualize 100 TB of the 3 PB in his shop. "It works well, although we don't run our whole business on it," Ferraro said. "There are a lot of players out there, and a lot of ways to do virtualization. We want to get out of the business of managing every little spindle. You have to get past that, and this helps."

Marty LeFebvre, who manages the data centers of Nielsen Media Research, uses the array-based virtualization in Hitachi Data Systems' Tagmastore SAN to virtualize part of the 2 PB he manages. He says HDS does a good job of heterogenous virtualization, which is important in a shop using storage products from many vendors. "You name it, we're probably running it," he says. "Contrary to what other three-letter vendors tell you, their stuff runs just fine behind [Tagmastore]."

EMC's switch-based Invista virtualization product remains the wild card in storage virtualization. Invista didn't exactly wow early users after it was launched in 2005. EMC gave a sneak peak at Invista 2.0 at last summer's EMC World show, claiming better scalability and performance, but has neither officially announced the upgrade nor said when it will be available. One industry source said Invista 2.0 will be primarily a tool to migrate data across arrays.

Jackson Shea, technical lead for storage administration at the Portland, Ore.-based Regence Group consortium of heathcare firms, is using IBM's SAN Volume Controller (SVC) appliance to virtualize 500 TB of data on EMC and IBM storage arrays. "I'm still waiting for it in the switch because that's where it makes more sense," he said.

But Shea says he got tired of waiting for Invista and went with SVC. "We wanted to begin reaping the benefits," he said. "We started slow, but ramped up quickly. It gives us the flexibility to manage 500 TB. The more servers we put behind [SVC], the better we're able to manage our environment."


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