Microsoft Still Cleaning Up With Windows

IBM's mainframe servers, running its z operating system, have been on a growth trend for over a year, according to IDC. Revenue for z servers grew 4% year-over-year during the quarter, to $1.2 billion. System z accounts for 9.5% of all server revenue and was the only platform outside of Linux and Windows to see revenue growth in the quarter.

Unix took in $4.2 billion in revenue in Q2, according to IDC. By revenue, Unix had 31.7% of the server market, reflecting the higher prices that mainframes capture.

Revenue for Windows on servers first surpassed Unix in 2006, says Jean Bozman, research vice president in IDC's worldwide enterprise server group.

Just as prognosticators have predicted that Windows will be threatened by virtualization, they say the same for the server market.

"We believe that virtualization reduced the x86 server market by 4% in 2006, and by 2009 it will have a far greater impact," Gartner analyst Thomas Bittman said at that firm's Infrastructure, Operations and Data Centre Summit in Australia in May.

But IDC doesn't see it that way.

"People had been concerned that with the ... adoption of virtualization we would see a slowing" of the server market, Bozman said. "But we saw an acceleration," particularly in x86 equipment, probably due to virtualization.

"That's why we provide the x86 cut on this: It's the leading [architecture] for the server," she said.

For now, the server environment is growing from the plethora of new Web 2.0 applications, online gaming, the building of server farms by online services companies, and upgrading of data center equipment and software at corporations, Bozman says

And as long as servers sell, so do operating systems. That continues to bode well for the reigning champion from Redmond, Wash.