Keep the following in mind when booting a system:
After a system is shut down, it is booted by using the boot command at the PROM level on a SPARC system or by using the boot command at the Primary Boot Subsystem Menu on an Intel system.
A system can be rebooted by turning the power off and then back on. This is not a clean shutdown because system services and processes are terminated abrubtly. However, turning a system's power off and back is an alternative for emergency situations.
SPARC and x86 systems use different hardware components for booting. These differences are described in Chapter 10, The Boot Process (Reference).