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

Troubleshooting from historic issues


The first instinct for a Data Collector would be to simply run through the same troubleshooting steps from Chapter 5, Network Troubleshooting. The Adaptor and Educated Gusser troubleshooters, however, knowing the issue a few days ago was due to a static route would simply log in to the database server first and check for the same static route.

Maybe someone simply re-added it by mistake, or the route was not fully removed from the system's configuration files:

[db]# ip route show
default via 10.0.2.2 dev enp0s3  proto static  metric 1024
10.0.2.0/24 dev enp0s3  proto kernel  scope link  src 10.0.2.15
169.254.0.0/16 dev enp0s8  scope link  metric 1003
192.168.33.0/24 dev enp0s8  proto kernel  scope link  src 192.168.33.12

Unfortunately, however, our luck is not that good; from the results of the ip command, we can see that the static route from Chapter 5, Network Troubleshooting, is not present.

Since the route is not present, we will need to start again...