Chapter 14. System Startup and Shutdown | HP Certified: HP-UX System Administration

Chapter Syllabus

14.1 Introduction to the Boot Process

14.2 Processor Dependent Code

14.3 Boot Area on the System Disk

14.4 Initial System Loader

14.5 Loading the HP-UX Kernel

14.6 The init Process

14.7 Runlevels

14.8 Adding a Program to Run at Boot Time

14.9 System Shutdown

Understanding of the system startup and shutdown processes is very important both for routine system administration and troubleshooting. Every HP-9000 server or workstation is supplied with boot code that resides on ROM. As soon as you power on the system, this code executes and performs self-tests and some initialization tasks. It then loads the HP-UX kernel and hands control over to it. The kernel does a number of system initialization tasks before you get a login prompt on your console or terminal. This chapter covers in detail all of the processes that take place from system power on to the display of the login prompt.

In the beginning, you will see an overview of the boot process. The boot process starts from processor dependent code (PDC) that resides on ROM in your system. You will learn how to work with PDC and use its commands by interrupting the boot process. During the boot process, the PDC checks for boot area on the primary boot disk. You will learn the structure of the boot area to build an understanding of this part of the boot disk. The initial system loader (ISL) is used to load the kernel into memory. Its knowledge is important if you need to boot your machine in single- user mode. You have to rebuild the HP-UX kernel many times, and ISL helps you boot from an old kernel if your new kernel is misconfigured and fails to boot. You will also see how the autoboot works and how to enable or disable it.

Once the HP-UX kernel is loaded into memory, it initializes other processes. The init process is the most important of all of these. It is responsible for most of the system initialization. When you study the section containing information about the init process, you will see the structure of its configuration file and how it performs automatic initialization of other processes at different stages of the boot process.

Runlevels show the system state at a particular instant, and these are also controlled by the init process. You will see which runlevels are supported on HP-UX and what the function is of each. Changing system states by changing runlevels is also explained at this stage.

Many times you need to perform a task right after the system boots up. You may also need to run a program at the boot time. You will find a complete example of how programs are started and stopped during the system startup and shutdown processes. In the last part of this chapter, the shutdown process will be presented. You will see the difference between the shutdown and reboot commands.

After going through this chapter, you will understand the startup and shutdown processes and the different stages that involve these processes. In addition, you will have knowledge of commands and utilities that are used for this purpose. Having a good understanding of this process, you will be able to troubleshoot any HP-UX startup or shutdown problem.

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