Upgrading the Operating System
An operating system upgrade merges the new version of the Solaris operating environment with the existing files on the system's disk. An upgrade saves as many modifications that you have made to the previous version of the Solaris operating environment as possible.
Backups Make sure that you back up your entire system and check the backup before performing an upgrade.
You can upgrade any system that is running the Solaris 7, 8, or 9 software. You can also update the Solaris 10 Update release if your system is running an older version of the Solaris 10 software. In this chapter, I will be describing how to perform an initial installation and will not be performing an upgrade. You'll see, however, in the later section "Using the Interactive Installation Process (suninstall)," that after the system identification portion of the installation process is complete, suninstall will ask you if you want to perform an upgrade.
You cannot upgrade your system to a software group that is not installed on the system. For example, if you previously installed the end-user Solaris software group on your system, you cannot use the upgrade option to upgrade to the developer Solaris Software group. However, during the upgrade, you can add software to the system that is not part of the currently installed software group.