SPARC platforms that support the Oracle VM Server for SPARC software are preinstalled with the Oracle Solaris 10 OS or the Oracle Solaris 11 OS. Initially, the platform appears as a single system hosting only one operating system. After the Oracle Solaris OS, system firmware, and Logical Domains Manager have been installed, the original system and instance of the Oracle Solaris OS become the control domain. That first domain of the platform is named primary, and you cannot change that name or destroy that domain. From there, the platform can be reconfigured with multiple domains hosting different instances of the Oracle Solaris OS.
Base your decision about which Oracle Solaris OS version to run on the primary domain on your requirements and any potential feature differences between Oracle Solaris 10 and Oracle Solaris 11. See Oracle Solaris 11.1 Release Notes and Transitioning From Oracle Solaris 10 JumpStart to Oracle Solaris 11.1 Automated Installer .