Users who purchase Sun hardware typically get support contracts that cover their hardware and software needs as well. But Sun officials say that the use of Solaris on hardware not manufactured by Sun has created the need for a support program aimed at those users.

"Up until about a year ago, we were really only selling Solaris on Sun hardware, so there wasn't a need for these types of individual subscription plans," said Peder Ulander, Sun's vice president of software marketing.

The company has had a support plan for Solaris to address the needs of these users, but most of the support has been offered on a time and material basis. There are now a variety of prices and plans, including a US$49-per-incident support plan or a $240-per-year subscription for up to a two-socket system. There are other subscription price levels to support multiple deployments, as well as custom pricing options.

Sun today also said it is adding new features to Solaris, including new security functions, such as Secure by Default Networking, which automatically improves its network security. Sun also intends to add Xen hypervisor virtualization technology by midyear.

Charles King, an analyst at Pund-IT Research in Haywood, Calif., said he doesn't believe subscription pricing will influence customer decisions on which operating system to use. He said those decisions are based on a range of factors, such as operating system functionality and the relationship a vendor has with its customers.