Install the Solaris 7 software on the server or standalone system using the software installation procedures given in Solaris 7 (SPARC Platform Edition) Installation Library or Solaris 7 (Intel Platform Edition) Installation Library. These are also known as the Start Here cards.
The Solaris 7 Interactive Installation program has a preserve screen that enables you to preserve existing file systems during installation. This is a good way to preserve any SunOS release 4 file systems so you do not have to restore them.
If you cannot preserve a SunOS release 4 file system or you choose not to (because you want to change how the system's disks are partitioned), you should create new file systems with sufficient disk space for the SunOS release 4 file system that you want to restore (using the disk space requirements you recorded earlier). Then you can restore the SunOS release 4 file systems into the new file systems after Solaris is installed.