Technical data

Starting Up and Shutting Down the System
Concept Section
System shutdown procedures Section 4.8
The order of shutdown events Section 4.8.2
4.1 Understanding Booting and System Startup
Booting is the process of loading system software from the system disk into
processor memory. When you boot your system, it automatically performs a series
of tasks to start up your system. These tasks are collectively known as system
startup.
You must have installed the operating system before you boot the system for the
first time.
Booting procedures vary for different computers. For example, computers with
console storage devices use a boot command procedure. You can copy and edit this
command procedure to specify the location of the system disk. Other computers
have an internal memory device that provides the name of the system disk.
On Alpha systems, you cannot boot from a magnetic tape device.
4.1.1 Booting and Startup Processes
Together, the booting and startup processes comprise the following steps:
1. You enter the BOOT command. The boot block, a fixed location on disk,
points to the primary bootstrap image, which is loaded from disk into
main memory.
On VAX systems, the primary bootstrap image is VMB.EXE.
On Alpha systems, the primary bootstrap image is APB.EXE.
The primary bootstrap image allows access to the system disk by finding the
secondary bootstrap image, SYS$SYSTEM:SYSBOOT.EXE, and loading it
into memory.
2. SYSBOOT.EXE loads the system parameters stored in the default parameter
file into memory. (For more information about the default parameter file and
loading of system parameters at boot time, see Section 4.2.)
If you are performing a conversational boot, the procedure stops and displays
the SYSBOOT> prompt. (For information about conversational booting,
see Section 4.1.3.2.) Otherwise, SYSBOOT.EXE loads the operating system
executive into memory and transfers control to the executive.
3. When the executive finishes, it executes the SWAPPER process.
4. The SWAPPER creates the SYSINIT process.
5. Among other actions it performs, SYSINIT creates the STARTUP process.
6. STARTUP executes SYS$SYSTEM:STARTUP.COM (unless you
indicated another file using SYSMAN, SYSGEN, or conversational
boot). STARTUP.COM executes a series of other startup command
procedures, including SYSTARTUP_VMS.COM. (For more information
about STARTUP.COM, see Section 4.1.4. For more information about other
startup procedures, see Section 5.2.1.)
The current values of system parameters are written back to the default
parameter file.
4–2 Starting Up and Shutting Down the System