The server market is rebounding from three years of slowing growth, according to the latest IDC numbers.

IDC said that the server market grew 6.3 percent year-over-year to $13.1 billion in the second quarter of 2007. The research firm attributes this growth to users refreshing the servers used in their datacentres and to expanded distributed-workload deployments.

Servers priced at under $25,000 had the largest growth at 11 percent year-over-year, while growth of midrange enterprise servers (costing $25,000 to $499,000) grew by 0.2 percent, and high-end enterprise servers (costing more than $500,000) showed a 1.7 percent increase.

IBM led the market with a 31 percent revenue share, followed by HP with over 28 percent. Sales of IBM's System x, System z and System p servers accounted for the majority of the company's server revenue, while HP's growth came from ProLiant and BladeSystem servers, IDC said. IBM mainframes running the z/OS operating system accounted for 9.5 percent of all server revenue.

Sun's server revenue grew 5.6 percent year-over-year; the company is the No 3 player with 13.1 percent of the market. Dell, which showed more than a 20 percent revenue growth in x86 servers, follows Sun.

On the operating system front, Linux servers represented 13.6 percent of server revenue. Microsoft Windows accounted for 38.2 percent of server revenue, and Unix system revenue tallied in at 31.7 percent of the market.

In x86-based servers, HP led the market with a market share of more than 35 percent, followed by Dell with more than 22 percent, then IBM with a 17.5 percent share.

The blade-server market also soared, with revenue growing 36.7 percent year-over-year. Blade servers accounted for $875 million, or 6.5 percent of the server market. HP held more than 47 percent of the blade-server market, followed by IBM with 32.3 percent.