According to a recent operating system report by Gartner, IBM's AIX operating system revenue grew 9.2 percent in 2010. IBM rarely reports OS-specific revenue gains, so this is interesting -- though certainly not unexpected -- news.

The Gartner study also tracked desktop PC operating system revenue, and combined with server OS revenue, Gartner says the combined worldwide market is now pegged at $30.4 billion, a 7.8 percent increase from 2009. Microsoft, with both server and desktop offerings, gobbled up nearly $24 billion of the OS pie.

Meanwhile, what about IBM's three key Power Systems operating systems: AIX, IBM i, and Linux?

"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," notes 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."

Among the three OSs owned by IBM, AIX experienced the highest growth at 9.2 percent due to the popularity of Power Systems, Gartner reported. IBM i OS revenue grew at 2.7 percent in 2010.

As for the competition, HP-UX was able to maintain modest growth at 3.7 percent in 2010. However, HP's revenue from proprietary UNIX and other proprietary OSs continued to decline because of the discontinuation of Tru64 and a decline in shipments of business-critical systems, such as NonStop and OpenVMS.

Oracle's software revenue from Solaris declined 3.2 percent in 2010 as end users were skeptical about Oracle's commitment to the Solaris platform -- although the company made several announcements to clear this anxiety, Gartner said. Oracle's Linux versions (also known as Unbreakable Linux) grew a small base almost 200 percent in 2010 -- which also showed Oracle's strategy to lessen its dependence on other vendors' UNIX or Linux OSs.

Red Hat has been dominating the commercial Linux (server) market. Revenue of Red Hat Enterprise Linux (RHEL) server license went up 18.6 percent to $592 million in 2010, taking a 58.2 percent share of the Linux (server) market. 

Additional information is available in the Gartner report "Market Share Analysis: Operating System Software, Worldwide, 2010."