Randy Frerking, the Enterprise Technical Expert for Wal-mart Stores, Inc., oversees a vast infrastructure that handles an incredible amount of traffic — traffic that peaks and troughs, sometimes dramatically, at the whims of shoppers everywhere.

In an interview with theCUBE during IBM Edge2015, Frerking put his experience into words. “I hired into Wal-mart back in 2007,” he explained. “We averaged about 200 million transactions a day through our online system. We run on a parallel Sysplex z/OS running CICS. And in 2009 we introduced what’s called Web Services using SOAP and SOA services. We now run about 500 million transactions a day. So we’ve more than doubled, almost two and a half times the volume, on the system.”

Predicting what the customer base will do a challenge

Uncertainty is an issue for their traffic loads, as well as volume, Frerking said. “So we have different holiday seasons where the volume increases, and we have no idea what that volume is going to be. It’s kind of hard to predict what the customer base is going to do, whether it’s from the dot com, from the mobile app or multi-channel platforms.”

In 2010, his team developed an application that functioned like a router. “It averages about 30 million transactions a day in production,” Frerking said. “So it’s not a real heavy application, but it gets a little bit of traffic. Well, last year on Black Friday, it scaled out to 190 million, six times the volume. So we didn’t have to change anything within the configuration of the CICS servers, or the Sysplex itself. That’s what Workload Manager does, that’s what the Sysplex does, is it manages the workload across the PLEX.”

An incredibly robust system

The system has proven incredibly robust.

“We had a customer-facing application about two years ago that needed an enterprise-distributed cashing solution for the next production roll-out,” Frerking said. “They’d purchased a product that was having performance and availability issues, so we decided to design and write a cloud-based service … cashing as a service solution. Since putting that into production, this application or this customer hits it about 15 million times a day, that’s over 10.5 billion calls over the last two years, with zero failures.”

This incredibly low failure rate is important for a network as vast as Wal-mart’s. But reliability isn’t its only concern, Frerking said.

“Wal-mart is about innovation. Because when you are innovative, you’re able to do things for the customer, and that’s what it’s all about,” he stated. “We can write code all day long, we can do really cool, fun stuff, and it’s absolutely meaningless if it does not benefit our customers.”

Watch the full interview below, and be sure to check out more of SiliconANGLE and theCUBE’s coverage of IBM Edge2015.