As the global economy recovered, worldwide operating system (OS) revenue totaled $30.4 billion in 2010, a 7.8 percent increase from 2009, according to Gartner (http://www.gartner.com). Mac OS X and Linux (server) and Mac OS were the fastest-growing subsegments in the client and server OS segments, respectively, while Microsoft maintained its leading position in the overall OS market, with 78.6% market share, says the research group.

"Generally, client OSs outperformed server OSs and grew 9.3% 2010, while the server OS segment grew 5.7%" says Matthew Cheung, principal research analyst at Gartner. "The long-pending demand for computer refreshment was unleashed as the economy stepped out from the economic turndown, which drove growth of client OSs."

Among client OSs, Mac OS was the fastest-growing subsegment in 2010 as the unit shipments of Mac desktop/laptop devices saw strong sales, although from a much-smaller basis. Windows client was still the largest client OS segment, with high-single-digit growth, particularly driven by adoption of Windows 7 and the imminent end of life (EOL) of Windows XP.

Mac OS X grew 15.8% to a size of US$520 million in 2010, fueled by the strong sales of Mac desktops and laptops. Apple's making of Mac OS as a "cool" client computing OS has attracted a group of loyal customers on Mac devices and platforms, says Gartner. Apple's continuous innovations in mobile devices, such as smartphones and tablets, have prompted sales of other Apple devices and will continue to drive Mac sales, according to the research group.

"In the server OS market, Linux (server) was the fastest-growing subsegment in 2010 as end users adopted more open-standard systems. Within the Unix OS market, IBM AIX had high single-digit growth, but Unix generally experienced modest or negative growth," says Alan Dayley, managing vice president at Gartner. "The EOL threat for Unix OSs such as Tru64 and NetWare pushed the 'other proprietary Unix' subsegment down 39.6 percent in 2010 as some vendors retired their proprietary Unix and moved users to more open systems."

Microsoft held the largest market share of the worldwide OS software segment, with 78.6% share in 2010. The distant second- and third-place vendors were IBM and HP, with 7.5% and 3.7% share, respectively. Oracle climbed up the ranking from No. 8 in 2009 to No. 4 in 2010 by acquiring Sun Microsystems' Solaris business in April 2009.