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System Management Concepts: Operating System and Devices

Chapter 1. System Management

System management is the task of an individual who is usually referred to, in UNIX literature, as the system administrator. Unfortunately, only a few system administrator activities are straightforward enough to be correctly called administration. This and related guides are intended to help system administrators with their numerous duties.

Topics covered in this chapter are:

The System Administrator's Objectives

The system administrator has three main objectives:

To achieve these objectives the system administrator must understand more than just the structure and interaction of the hardware and software under their control. They must also understand the interconnected environment in which almost all current systems exist and the effects that environment has on function and performance of the local system.

A System Is More Than a Computer

A contemporary computer system includes a number of hardware, software, and information elements that must work cooperatively if the system is to satisfy the needs of its users. The main elements and their management functions are:

Unique Aspects of System Management

This operating system provides its own particular version of system-management support in order to promote ease of use and to improve security and integrity. This chapter presents information on these unique features:

Available Interfaces

In addition to conventional command line system administration, this operating system provides the following interfaces:

Unique Features of the Operating System

Following are brief discussions of unique system-management features of the operating system.

Logical Volume Manager

The Logical Volume Manager (LVM) allows logical volumes to span multiple physical volumes. Data on logical volumes appears to be contiguous to the user, but can be discontiguous on the physical volume. This allows file systems, paging space, and other logical volumes to be resized or relocated, span multiple physical volumes, and have their contents replicated for greater flexibility and availability.

For more detailed information, see the Logical Volume Storage Overview.

System Resource Controller

The System Resource Controller (SRC) provides a set of commands and subroutines for creating and controlling subsystems and is designed to minimize the need for human intervention in system processing. It provides a mechanism to control subsystem processes by using a command-line C interface. This allows you to start, stop, and collect status information on subsystem processes with shell scripts, commands, or user-written programs.

For more detailed information, see the System Resource Controller Overview.

Object Data Manager

The Object Data Manager (ODM) is a data manager intended for the storage of system data. Many system management functions use the ODM database. Information used in many commands and SMIT functions is stored and maintained as objects with associated characteristics. System data managed by ODM includes:

Software Vital Product Data

Certain information about software products and their installable options is maintained in the Software Vital Product Data (SWVPD) database. The SWVPD consists of a set of commands and Object Data Manager (ODM) object classes for the maintenance of software product information. The SWVPD commands are provided for the user to query (lslpp) and verify (lppchk) installed software products. The ODM object classes define the scope and format of the software product information that is maintained.

The installp command uses the ODM to maintain the following information in the SWVPD database:

Workload Manager (WLM)

Workload Manager (WLM) lets you create different classes of service for jobs, as well as specify attributes for those classes. These attributes specify minimum and maximum amounts of CPU, physical memory, and disk I/O throughput to be allocated to a class. WLM then assigns jobs automatically to classes using class assignment rules provided by a system administrator. These assignment rules are based on the values of a set of attributes for a process. Either the system administrator or a privileged user can also manually assign jobs to classes, overriding the automatic assignment.

man Command

The man command is used mainly to access reference information on commands, subroutines, and files. For example, to view information on the gprof command, enter:

>man gprof

Most of the information displayed is actually taken from formatted HTML files. Many system managers find using the man command more convenient than starting a web browser session when they simply need to find out about a certain flag or the syntax of a given command.

For more information on the man command, see the AIX 5L Version 5.1 Commands Reference. Also see Online Documentation and man Command for BSD 4.3 System Managers.

Operating System Updates

For detailed information on software and termed service updates, see Installing Optional Software and Service Updates in AIX 5L Version 5.1 Installation Guide.

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