5.1 Chapter Objectives

• Increase system availability by developing system-startup procedures that are clear and concise and follow commonly practiced standards

• Demonstrate techniques that will reduce system-boot time

• Discuss aspects of DCL error processing that are important to system-startup procedures

• Provide techniques for automatically detecting and reporting system-startup errors

• Provide a fully developed set of template startup procedures to tailor your system

5.2 Introduction

System startup is a continuation of the system-initialization process initiated by a system boot. For the purpose of this book, system startup involves all system-initialization steps that occur in the context of a process, rather than in system context. Chapter 4 only presents booting steps performed in system context; thus, this chapter elaborates on the rest of the boot sequence.

Sometimes system-startup procedures fail because of procedure bugs or hardware problems. By default, system-startup errors and messages are displayed on the console terminal. Unless you read and understand every line displayed on the console, you will miss key messages indicating startup errors. You need a more reliable method of identifying them.

System startup is an involved process about 50 different command procedures are executed. To minimize downtime, you should thoroughly understand when, where, and why each procedure is executed. In addition, many startup procedures depend on the successful completion of prior procedures. You should understand system-startup dependencies so that you preserve the correct startup order when you make modifications.

5.3 System-Startup Sequence

System startup involves the execution of two general sets of command procedures:

1. Site-independent startup procedures