With the availability and affordability of higher-capacity storage and bandwidth, enterprises are now pushing terabytes or even petabytes of replication and disaster recovery (DR) traffic between data centers. But many wide area network (WAN) pros learn the hard way that bigger pipes don't always ensure that
"When you throw in a 10-gig link ... [the server] only becomes more sensitive to [latency] because it expects to get this tremendous amount of throughput," said Jamie Whittle, director of system architecture at Peak 10, a managed IT services company based in Louisville, Ky. "It's not just a 1x or 2x fall. It is an exponential drop."
Linux-based servers tend to handle replication traffic faster than Windows servers, but neither is optimized for the WAN, Whittle said. Introducing any latency on a higher-capacity WAN link—even the 10 milliseconds between Peak 10's Louisville and Charlotte, N.C., data centers—magnifies any performance issues with the replication process itself, he said.
WAN emulators critical as enterprises shift from gigabit to 10 gigabit links
"There is so much data out there, and the virtual machines and physical machines are getting so incredibly large that [gigabit] connectivity between two [data centers] isn't going to be enough," Whittle said. "We're getting to the point where 10 gig is necessary ... and as we start moving down this path, we wanted to know if we could reliably replicate [data] between two data centers at a full 10 gig—maxing out our pipes—[without compromising] our SLAs."
Apposite Technologies recently announced its Netropy 10G2 appliance—a WAN emulation engine that can simulate customized conditions on two separate 10 Gbps bidirectional links—in response to rising 10 Gbps adoption.
Competitor Anue Systems' Anue Network Emulator has supported 10 Gbps on its Hawaii hardware platform since the end of 2004. Shunra Software has offered a 10 Gbps WAN emulator since 2008.
"We've been hearing this for years, and we heard a lot of it before the financial crisis in 2008: Everyone was saying 10 gig is coming ... and then it fell by the wayside," said DC Palter, president of Apposite. "Suddenly, this year, 10 gig is happening and we're seeing it [adopted] across the board—everyone from financial institutions to large companies are moving to a 10-gig infrastructure ... and in many cases, they're using it [between] multiple data centers."
WAN emulators simulate inter-data center traffic
Whittle plans to deploy Apposite's 10G2 appliance at Peak 10 within the next month—as soon as construction of a new data center is complete—to test the company's ability to support increasing customer demand for replication between three "hub" data centers with 10 Gbps connections.
He hopes the 10 Gbps WAN emulator will help Peak 10 comply with its SLAs. However, he would like to see Apposite add more ports to the new device so that he can emulate more simultaneous high-speed connections.
Xingzhe Fan, a chief scientist at Aspera Software in Emeryville, Calif., which develops high-speed file transfer software, has deployed Apposite's 10 Gbps WAN emulators to test its own software against high-performance storage appliances or on enterprise customers' multigigabit WANs crossing continents and oceans.
For our [enterprise] customers, 1% or 2% [packet loss] is not uncommon, so it's very important for us to demonstrate that [with our software] their throughput won't drop when you have that much packet loss.
Chief Scientist, Aspera Software
"For our [enterprise] customers, 1% or 2% [packet loss] is not uncommon, so it's very important for us to demonstrate that [with our software] their throughput won't drop when you have that much packet loss," he said. "We need to explore all of these combinations [of WAN conditions]."
W. Kelly Reed, network engineer at a U.S. freight rail company, is halfway through a large SAP deployment across more than 200 locations. He is emulating that application via Shunra's VE appliance to eliminate the need to test at remote locations. The appliance, which Shunra recently rebranded as PerformanceSuite, continues to be part of all testing and has become "one of the most valuable tools I have ever experienced," Reed said.
Although he has no immediate need to test inter-data center traffic at 10 Gbps, Reed said the WAN emulator would unquestionably be part of any initiative.
"If we run across the need, it will be part of the process," he said.
WAN emulators not a perfect science
However, not all WAN emulators are created equally. Colleen Jakes, director of information services at TopLine Federal Credit Union in Minneapolis, describes her experience with WAN emulators as "limited and somewhat jaded" based on her experience with one in a prior role about five years ago.
"The IT group attempted to use a WAN emulation to determine the performance of Oracle business apps across a global WAN. The emulator said one thing, [but] the actual application did something completely different," Jakes said. "We had depended on the emulator to be correct, launched the main business application globally and the application tanked our WAN. We had to go offline for two additional weeks to allow for WAN bandwidth upgrades."
Apposite's WAN emulator doesn't flawlessly simulate the actual performance on Peak 10's WAN, but Whittle said its emulation is accurate enough to be reliable.
"It's something that doesn't exactly replicate our production environment, but it's … close enough," Whittle said.
Let us know what you think about the story; email: Jessica Scarpati, News Writer.