Sun grew server revenue by 15,5% to $1,6bn in the second quarter, from $1,4bn in the second quarter of 2005, according to IDC's Worldwide Quarterly Server Tracker. Its market share grew to 12,9% from 11,2% in the year ago quarter. The growth helps Sun reclaim third place on the market share ranking of the top server vendors, pushing rival Dell back to fourth. Sun ranked fourth, and Dell third, in the previous three quarters.

Sun was also the only major vendor to report second quarter revenue growth, while others reported declines.

"Sun was the big winner," says Jed Scaramella, an enterprise server research analyst at IDC, who attributed Sun's improvement to the strength of its UltraSPARC processor servers and earlier adoption than rivals of 64-bit Opteron chips from Advanced Micro Devices.

Still, Sun's server revenues were less than half of either of its main rivals.

IBM maintained its lead at 31% on revenue of $3.8bn, down by 2,2% from a year earlier. Hewlett-Packard ranked second with a 27,8% share, on sales of $3,4bn, down by 1,7%. Dell's share was 10,3% on a 1,3% decline in revenue to $1,27bn. Fujitsu Systems ranked fifth with a 4,5% share on a slight 0,5% revenue gain to $554m.

The report also shows sales only grew at the lower end of the market. Sales revenue for volume servers (those selling for less than $25 000) grew by 6,2% year over year, while sales of midrange servers ($25 000 - $499 000) fell by 3,5% and high-end ($500 000 and up) fell by 6,9%. IDC attributes the shift to the improved technology in volume servers that offers improvements in performance, system management and other capabilities at an affordable price.

IBM remains the server leader by being "all about the total solution," says Scaramella. "It is all about global solutions rather than just selling the components."

The report also noted unit shipment growth of a modest 8,3% in the second quarter year over year, the eighth consecutive month of slow growth after double digit growth rates in 2004 and 2005.

Revenue growth was strongest in the US market (3,6%) and Asia/Pacific excluding Japan (2,6%) while weaker elsewhere.

Revenue growth for x86-powered servers continued, but at a modest 3,3% to $5,9bn, on unit sales growth of 9,8%. The x86 server continues to grow as customers "migrate server workloads to industry-standard architectures," says Scaramella.

The blade server market showed strength with 37,1% revenue growth on a 29,7% jump in unit sales.