In this chapter, we walked through the troubleshooting process by using an issue that can easily occur in the real world. We iterated through Steps 1, 2, and 3 of the troubleshooting process to collect data, establish a hypothesis, and resolve the issue; these steps were covered in detail in Chapter 1, Troubleshooting Best Practices. We then used several commands and log files that we learned about in Chapter 2, Troubleshooting Commands and Sources of Useful Information as well as a few new ones.
While learning the commands used in this chapter is important for any systems administrator working with web applications, it is more important to look at the process that we followed. We started working on the problem with no prior knowledge of the environment or application, but with some basic data collection and trial and error, we could resolve the problem.
In the next chapter, we will use this same troubleshooting process and similar tools for troubleshooting performance issues.