SANs: Taking Advantage of Storage Pools

When your job is to run data centers that provide applications and storage to the Agriculture Department, the White House, the Labor Department, the Federal Aviation Administration and other federal agencies, downtime is not an option. That’s the task of USDA’s National Information Technology Center. NITC provides computer services not just to the more than 100,000 employees of USDA but also to agencies throughout the federal government.

“We strive to achieve near-100 percent availability,” says Clay Cole, chief of the NITC’s Business and Product Management Branch. “Hosted applications at NITC vary in criticality from one end of the spectrum to the other, up to and including applications that support emergency personnel in life-threatening situations. The cost of infrastructurewide failure would be catastrophic to us and our customers.”

To maintain that level of high availability, NITC relies on advanced features of storage area networks to create multiple redundant pools of always-available storage. Through storage virtualization technology, which includes disk cloning and replication to geographically dispersed locations, NITC can “create redundant copies of data with potentially less-expensive tiers of storage,” Cole says.

At NITC, the Fibre Channel SAN infrastructure combines servers from HP, IBM, Sun Microsystems and Unisys with a Hitachi Data Systems disk array and StorageTek tape library — all linked by Brocade Silkworm switches. The center has a primary SAN plus an alternate SAN at a separate facility where it replicates data to assure continuity of operations.

Into the Pool

SANs centralize disparate storage devices across the network into a single pool, from which storage capacity can be allocated in whatever amounts are needed, to whatever applications need it. Essentially, a SAN makes just the right amount of capacity available to each application, regardless of the capacities of the actual physical hard drives or other storage the data ends up on.

The ability of a SAN to group and reassign storage as needed helps NITC control its storage costs. “A lot of organizations buy much more storage than they need,” says Laura DiDio, principal analyst at Information Technology Intelligence Corp. (ITIC) “With SANs, you can assign these empty spaces to any server that needs new storage.”

Another benefit is the ability to manage storage remotely, an impossibility with traditional direct-attached storage. “With a SAN,” says DiDio, “you manage all storage from a single console, so you can centralize backup and recovery and even install new storage on the fly wherever it is needed.”

Being able to remotely backup and restore files, re-assign storage and migrate data contributes to the high availability of SAN-based storage. “Nowadays, people can’t afford downtime,” says DiDio. “Fifteen or 20 years ago, 99 percent was considered high availability. Today, 99 percent could mean 90 hours of downtime a year.”

For an organization such as USDA, with its 100,000-plus employees, that would be millions of lost hours of employee productivity — clearly an unacceptable proposition. “A single hour of downtime,” notes DiDio, “can cost thousands to millions of dollars.”

At NITC, the many benefits add up to a superior storage solution that USDA organizations and other agencies that the center serves can rely on. “The SAN has helped reduce downtime associated with the availability of disk storage, provided high-performance capacity and enabled economies of scale to limit the overall cost,” says Cole.