Many have replaced tape archiving with electronic data backup and added redundant voice and data lines or satellite communications systems. Power generation capabilities have been improved, and some companies have even dug wells in an attempt to ensure that they have a reliable water supply. New contracts have been signed with disaster recovery providers.

But Katrina's lessons have exacted a financial and emotional price on many of the people who have strived to reassemble and improve their IT operations over the past year.

"The hardest part of this is fatigue," said Kevin Bassett, who manages IT at Kirschner & Co., a New Orleans-based furniture retailer. Bassett added that it has taken an unrelenting effort to deal with the professional and personal challenges caused by the storm. "We've been doing this every single day for a year now," he said.

Bassett is a member of the National Guard who was called to duty just before Katrina struck and assigned to work in the Louisiana Superdome, where thousands of people took shelter from Katrina and then waited for days to be evacuated. In a car, Bassett provides a tour of once-flooded neighborhoods, where the devastation extends mile after mile. In St. Bernard Parish, just outside of New Orleans, he points out his uncle's house, which was covered with water and now stands empty and ruined in a deserted subdivision. Not too far away, where the waters didn't rise as high, his grandparents are rebuilding their home.

Kirschner runs the IT operations that support its retail business from a 250,000-square-foot warehouse in New Orleans. After the levees along some of the city's canals failed, the warehouse became an island in a six-foot-deep lake and was completely cut off, Bassett said. The steps he has taken since Katrina include installing redundant communications lines and satellite capabilities.