Shopping Site Braces for Holidays

Online shopping during the holiday season relieves much of the stress of battling crowds at the mall -- and places that stress on the infrastructure and IT teams at online retail sites.

With Black Friday, Black Monday, and other shop-happy days coming, admins such as Shopzilla's Burzin Engineer (his name, not his job title) want to make sure their shopping sites can handle the loads to avoid any black eyes and red ink for their businesses.

"An hour's downtime on one of those days could cost between $80,000 and $200,000, depending on the hour," says Engineer, Shopzilla's director of infrastructure. "If it's peak time, it's easily $200,000. Downtime's not an option. It's time for people's resignations if that happens."

A week from today is Black Friday, widely considered the kickoff of the holiday shopping season. That's followed by Black Monday, also known as Cyber Monday, when millions return to work after the Thanksgiving weekend, log on, and promptly hit their favorite online retail sites.

But the busiest day for online shopping usually comes in mid-December, when people realize the deadline for getting their gifts shipped on time is rapidly approaching. Engineer expects that day to come around Dec. 11 this year. He has the date circled because "that's the day when all the geeks typically go shopping. They say 'Oh, shoot, I need to go online because I'm running out of time for them to ship.' That's the busiest day. Black Friday is more for the malls."Still, with Shopzilla getting 1.3 million unique visitors on Black Friday last year, it's not exactly a slow day online. Engineer says holiday season brings about 70 percent more unique visits than the rest of the year, and about a 35 percent increase in storage I/O requests. He says redirects from Shopzilla to merchants' sites usually double this time of year.

"It stresses our entire infrastructure. If you do not show a page to a consumer in four seconds he's gone, he's bye-bye. It's a Catch-22 for us. On those days we would like things on the site to be pseudo-static and not updated in real time because so many people are pounding on us. At the same time, that's the day merchants want the most relevant information to be available to consumers. In order to sustain load and constant refreshing of data, we need to refresh data while we're at peak load."

The site lists about 60 million items from around 80,000 stores, with 75 million images online. Shopzilla has 35 Tbytes of storage on 3PAR InServ S800 SAN and ONStor Bobcat 2200 NAS gateways the two vendors co-market as a UtiliCat Unifited Storage system. (See ONStor, 3PAR Double-Team.)

How does Shopzilla prepare for the holiday rush?

"We do a code freeze 15 days before [Black Friday]," Engineer says. "After that, no more changes to our system. And before that, we typically add anywhere from 30 percent to 50 percent more capacity and application servers. This time of year, we keep the disks crunching."This is the second holiday season Shopzilla has the 3PAR-ONSor combo. Engineer says he likes the scalability they offer with 3PAR's thin provisioning and dynamic optimization features.

"We can add disk and have data repartitioned across the disks. That was the key missing ingredient. Before we would have to bring the system down, and copy data over to new storage. It was massive downtime."

This year, Shopzilla beefed up its ONStor cluster from two heads to four, and began replication of its customer-facing applications to a second data center.

Engineer says the upgrades usually pay for themselves by spurring repeat business during the rest of the year. "After the holidays we go through another busy peak as people come back" with gift certificates, he says.

Then it's time to prepare for the next shopping holiday, which is more red than black. "The next big push is Valentine's Day. But that's nowhere near the amount of traffic as this time of year."Dave Raffo, News Editor, Byte and Switch