Sun Microsystems plans to announce a free version of its Solaris operating system Monday, taking a page that Red Hat tore from its playbook in 2003.

Anyone who registers with Sun will be able to use Solaris for free on servers with x86 processors, said John Loiacono, executive vice president of Sun’s software business. It’s not a totally free lunch, though: Sun will provide security updates in the free version but will charge an annual subscription fee for bug fixes and support.

Sun will begin the new pricing when it starts selling its new Solaris 10 version, scheduled to ship by the end of January, Loiacono said. The per-processor, per-year subscription will cost $120 for bug fixes, $240 for 12-hour support five days a week and $360 for 24-hour support seven days a week. For example, with premium support, the new Solaris 10 version will cost $1,440 per year for a server with four Opteron processors from Advanced Micro Devices.

The pricing strategy, to be announced at a quarterly product launch event in San Jose, Calif., is the first half of an ambitious effort to retrieve relevance that Solaris lost to Linux. The second half will arrive in 60 to 90 days as Sun releases the source code of Solaris under an open-source license, Loiacono said.