You must first upgrade your system to Solstice DiskSuite 4.0 and Solaris 2.5, using the instructions in the DiskSuite 4.0 Installation notes. Then you can use the instructions in the following subsections to upgrade to Solstice DiskSuite 4.2.1. Follow the upgrade procedure in the Solaris 2.5 and Solstice DiskSuite 4.0 product notes.