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

Identifying the issue

From the alert, we can see that our monitoring system was unable to perform ICMP pings to our company blog server. The first thing we should do is determine whether or not we can ping the server:

$ ping
PING ( 56 data bytes
64 bytes from icmp_seq=0 ttl=64 time=0.832 ms
64 bytes from icmp_seq=1 ttl=64 time=0.382 ms
64 bytes from icmp_seq=2 ttl=64 time=0.240 ms
64 bytes from icmp_seq=3 ttl=64 time=0.234 ms
--- ping statistics ---
4 packets transmitted, 4 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 0.234/0.422/0.832/0.244 ms

It seems that we are able to ping the server in question, so maybe this is a false alert? Just in case, let's attempt to log in to the system:

$ ssh -l vagrant
[email protected]'s password: 

Looks like we were able to log in and the system is up and running; let's start taking a...