DevOps Troubleshooting

Preface xiii Acknowledgments xix About the Author xxi Chapter 1: Troubleshooting Best Practices 1 Divide the Problem Space 3 Practice Good Communication When Collaborating 4 Favor Quick, Simple Tests over Slow, Complex Tests 8 Favor Past Solutions 9 Document Your Problems and Solutions 10 Know What Changed 12 Understand How Systems Work 13 Use the Internet, but Carefully 14 Resist Rebooting 15 Chapter 2: Why Is the Server So Slow? Running Out of CPU, RAM, and Disk I/O 17 System Load 18 Diagnose Load Problems with top 20 Troubleshoot High Load after the Fact 29 Chapter 3: Why Won't the System Boot? Solving Boot Problems 35 The Linux Boot Process 36 BIOS Boot Order 45 Fix GRUB 47 Disable Splash Screens 51 Can't Mount the Root File System 51 Can't Mount Secondary File Systems 55 Chapter 4: Why Can't I Write to the Disk? Solving Full or Corrupt Disk Issues 57 When the Disk Is Full 58 Out of Inodes 61 The File System Is Read-Only 62 Repair Corrupted File Systems 63 Repair Software RAID 64 Chapter 5: Is the Server Down? Tracking Down the Source of Network Problems 67 Server A Can't Talk to Server B 68 Troubleshoot Slow Networks 78 Packet Captures 83 Chapter 6: Why Won't the Hostnames Resolve? Solving DNS Server Issues 93 DNS Client Troubleshooting 95 DNS Server Troubleshooting 98 Chapter 7: Why Didn't My Email Go Through? Tracing Email Problems 119 Trace an Email Request 120 Understand Email Headers 123 Problems Sending Email 125 Problems Receiving Email 135 Chapter 8: Is the Website Down? Tracking Down Web Server Problems 141 Is the Server Running? 143 Test a Web Server from the Command Line 146 HTTP Status Codes 149 Parse Web Server Logs 154 Get Web Server Statistics 158 Solve Common Web Server Problems 163 Chapter 9: Why Is the Database Slow? Tracking Down Database Problems 171 Search Database Logs 172 Is the Database Running? 174 Get Database Metrics 177 Identify Slow Queries 182 Chapter 10: It's the Hardware's Fault! Diagnosing Common Hardware Problems 185 The Hard

Kyle Rankin is a system administrator for Quinstreet, Inc., the current president of the North Bay Linux Users Group, and the author of Knoppix Hacks and Knoppix Pocket Reference. Kyle has been using Linux in one form or another since early 1998. In his free time he does pretty much the same thing he does at work - works with Linux.