Here’s another sign that the holiday shopping season is upon us: Kohls.com was unavailable to online shoppers during part of the morning today.

The Kohl’s Corp. retail chain took down the site from about midnight until 9:30 a.m. Central time for scheduled maintenance. “In this case [it was] a planned performance test to further ensure we are prepared to meet peak demand moving into the holiday season,” says a spokeswoman for the chain, No. 26 in the Internet Retailer Top 500 Guide.

That the site’s downtime extended into the work and shopping day was perhaps a bit unusual, says Justin Noll, director of client experience for the site monitoring firm AlertBot.

“While this is a long time to take the web site offline, many retailers are doing this to prepare for Black Friday/Cyber Monday,” he says.