Unlike
VMware-dominated server virtualization,
storage virtualization poses more options and demands more
decisions from administrators, and storage administrators spent a
lot of time at Storage Decisions this week discussing the pros and
cons of those options.
One thing nearly everyone agrees with: Storage virtualization
can benefit practically everybody with networked storage. It's how
to get there that brings difference of opinions.
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, and that brings another
choice -- should the virtualization take place in a switch,
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 he estimated 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 in each
location.
"Our SAN is so modular now, if I need more infrastructure, I
simply add more infrastructure," he 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."
Yotko said thin provisioning let IAC buy 50 percent less disk up
front. It also improves application performance. "Each application
uses all the spindles," he said. "It goes where you need it when
you need it."
Paul Ferraro, storage manage of San Diego-based, telecom chip
vendor Qualcomm is also using 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 Nielsen Media Research's data
centers, uses Hitachi Data Systems array-based virtualization in
its 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 many vendors' storage. "You name it,
we're probably running it," LeFebvre 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 EMC World last summer claiming better scalability
and performance, but has not officially announced the upgrade or
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 heath care 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," Shea said. But he grew 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."