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
About the Author
About the Reviewers

Basic troubleshooting

The first test we should perform is a simple ping from the blog server to the database server. This will quickly answer whether the two servers are able to communicate at all:

[blog]$ ping
PING ( 56(84) bytes of data.
64 bytes from ( icmp_seq=1 ttl=64 time=0.420 ms
64 bytes from ( icmp_seq=2 ttl=64 time=0.564 ms
64 bytes from ( icmp_seq=3 ttl=64 time=0.562 ms
64 bytes from ( icmp_seq=4 ttl=64 time=0.479 ms
--- ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3006ms
rtt min/avg/max/mdev = 0.420/0.506/0.564/0.062 ms

From the ping command's results we can see that the blog server can communicate with the database server, or rather, the blog server sent an ICMP echo request and received an ICMP echo reply from the database server. The next connectivity we can test...