The best and safest command to do a clean shutdown or a reboot of a Solaris server is the 2 commands below. There are many commands with which you can achieve this. But if you have many scripts in init.d for application like Oracle DBand Oracle RAC. Then shutdown command is the way to go, also it prompts the users to save and shutdown their sessions.
shutdown -y -i6 -g0
shutdown -y -i5 -g0