Book Image

Red Hat Enterprise Linux Troubleshooting Guide

By : Benjamin Cane
Book Image

Red Hat Enterprise Linux Troubleshooting Guide

By: Benjamin Cane

Overview of this book

Red Hat Enterprise Linux is an operating system that allows you to modernize your infrastructure, boost efficiency through virtualization, and finally prepare your data center for an open, hybrid cloud IT architecture. It provides the stability to take on today's challenges and the flexibility to adapt to tomorrow's demands. In this book, you begin with simple troubleshooting best practices and get an overview of the Linux commands used for troubleshooting. The book will cover the troubleshooting methods for web applications and services such as Apache and MySQL. Then, you will learn to identify system performance bottlenecks and troubleshoot network issues; all while learning about vital troubleshooting steps such as understanding the problem statement, establishing a hypothesis, and understanding trial, error, and documentation. Next, the book will show you how to capture and analyze network traffic, use advanced system troubleshooting tools such as strace, tcpdump & dmesg, and discover common issues with system defaults. Finally, the book will take you through a detailed root cause analysis of an unexpected reboot where you will learn to recover a downed system.
Table of Contents (19 chapters)
Red Hat Enterprise Linux Troubleshooting Guide
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

What caused the high load average?


While we have identified what rebooted the server, we still have not gotten to the root cause of the issue. We still need to figure out what caused the high load average. Unfortunately, this would classify as information that is lost during a reboot.

If the system was still experiencing a high load average, we would simply be able to use top or ps to figure out which processes are using the most CPU time. Once the system was rebooted however, any process that was causing a high load average would have been restarted.

Unless these processes started causing a high load average again, we have no way of identifying the source.

$ w
 02:13:07 up  23 min,  1 user,  load average: 0.00, 0.01, 0.05
USER     TTY        LOGIN@   IDLE   JCPU   PCPU WHAT
vagrant  pts/0     01:59    3.00s  0.26s  0.10s sshd: vagrant [priv]

However, we are able to identify when the load average started to increase and how high it went. This information might be useful as we investigate further...