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

The analyst firm said that the server market grew 6.3 percent year-over-year to $13.1bn (£6.05bn) in the second quarter of 2007. The research firm attributes this growth to users refreshing the servers used in their data centres and to expanded distributed-workload deployments.

Servers priced at under $25,000 had the largest growth at 11% 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% increase.

IBM led the market with a 31% 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% year-over-year; the company is the No. 3 player with 13.1% of the market. Dell, which showed more than a 20% revenue growth in x86 servers, follows Sun.

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

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

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