Red Hat Enterprise Linux 5 Administration Unleashed

CHAPTER 20Monitoring SystemResourcesAlthough most users only think about their administratorswhen a problem occurs or when they suspect their systemhas been compromised, administrators spend a considerableportion of their time monitoring system resources to preventfailures. It is often a thankless job, but it can be very rewardingfor everyone, especially the administrator who doesn’thave to get out of bed at 3 a.m. to fix a critical problem thatcould have been prevented by intelligent monitoring.This chapter discusses how to monitor filesystems, systemprocesses, CPU utilization, physical and virtual memory,and the network subsystem in Red Hat Enterprise Linux. Italso details how to generate a system report for troubleshootingand where to find log files.Consider using all or some of the commands provided inthis chapter in custom scripts to alert you of problems thatmay arise. Refer to Chapter 11, “Automating Tasks withScripts,” for more information about writing custom scriptsand scheduling their execution at set intervals.IN THIS CHAPTER. Reporting Filesystem Usage. Reporting Disk Performance. Reporting System Processes. Reporting on the SystemProcessors. Reporting Memory Usage. Reporting on the NetworkSubsystem. Generating a System Report. Locating Log Files. Viewing Log Files withLogwatchReporting Filesystem UsageOne of the most critical system components to monitor isthe filesystem. If the filesystem becomes unavailable, thesystem is most likely incapacitated. Discovering problemsbefore the system goes down is key to being a successfuladministrator. For example, adding additional storage orcleaning off unneeded files when a disk has almost reachedcapacity is much better than waiting for the all disk space tobe used and then hearing from everyone that they can’twrite files to the disk. The first requires a scheduled actionduring a scheduled maintenance time, and the later requiresan immediate emergency operation, which can occur at anytime, including when access to the system is most required.