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

Checking whether the application is already running

One very common cause for this type of problem is simply that the application is already running. Some applications should only be started once, and the application itself will check whether another instance is running before completing a startup.

In general, if this scenario were the case, we would expect the application to print an error to the screen or the debug.out file. However, not every application has appropriate error handling or messaging. This is especially true for custom applications, and it seems to be true for the application we are working with as well.

At the moment, we are making the assumption that our issue is caused by another instance of the application. This is an educated guess based on debug messages and previous experience. While we do not have any hard facts (yet) that tell us whether another instance is running or not; this scenario is quite common.

This situation is a perfect example of an Educated Guesser using...