Thinking of consolidating storage? First look at your WAN latency

Storage Networking World - Many companies today are considering the idea of consolidating and centralizing their storage and servers that are dispersed among multiple locations. However, as Fanning/Howey Associates Inc. in Celina, Ohio, found, there are usually several steps that should precede centralization, including solving any WAN latency problems you might have.
And as Fanning/Howey also found, that doesn't mean just throwing more bandwidth at your current architecture. To the contrary, as the company discovered, it is possible to have more bandwidth than you are using and still suffer poor WAN performance due to extended latency.
Fanning/Howey, which does facilities planning and design for education organizations, operates 10 offices spread across five states in the Midwest. Although it maintains servers with storage at each office, the offices continually share files as they work on projects. In addition, the company runs Exchange locally at each office for e-mail. None of the data is stored centrally, which increases the cost of managing it. Altogether, the company operates 1.5TB of storage across 10 offices.
It was when the organization's WAN contract was up for renewal in late 2003 that information services manager Thomas Foreman analyzed his WAN usage -- only to find that the company was using only about one-third of the bandwidth it had been buying.
Yet even with a costly surfeit of bandwidth, moving data among the offices was slow, due to WAN latency. "The extra bandwidth only masked the latency problem," Foreman recalls.
Chance meeting
At a storage conference, Foreman bumped into Riverbed Technology Inc., a San Francisco-based start-up. Riverbed makes an appliance called Steelhead that speeds up the performance of data over WANs. Steelhead substitutes its more efficient protocol for TCP, chunks up the data into small (100-byte) pieces, tracks any changes to those pieces and adds compression, caching and TCP- and application-layer optimization. The upshot: It reduces latency, which speeds the data over WANs and increases the throughput.
"Riverbed was talking about how bandwidth doesn't solve the latency problem. They could have been talking about us," Foreman recalls. "Still, it sounded too good to be true."
Rather than take it on faith, Riverbed suggested Fanning/Howey participate in its try-before-you-buy program. The vendor would give Foreman two Steelheads for 30 days to test the technology. If it didn't fix the latency problem, Foreman could just send it back, no charge.
When the units arrived, Foreman installed one in the Dublin, Ohio, office -- a 20-minute procedure with some help from a Riverbed technician -- and the other in the Indianapolis office, the company's