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| Preface | |
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| Acknowledgments | |
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| About the Author | |
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| Troubleshooting Best Practices | |
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| Divide the Problem Space | |
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| Practice Good Communication When Collaborating | |
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| Conference Calls | |
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| Direct Conversation | |
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| Email | |
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| Real-Time Chat Rooms | |
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| Have a Backup Communication Method | |
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| Favor Quick, Simple Tests over Slow, Complex Tests | |
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| Favor Past Solutions | |
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| Document Your Problems and Solutions | |
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| Know What Changed | |
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| Understand How Systems Work | |
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| Use the Internet, but Carefully | |
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| Resist Rebooting | |
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| Why Is the Server So Slow? Running Out of CPU, RAM, and Disk I/O | |
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| System Load | |
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| What Is a High Load Average? | |
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| Diagnose Load Problems with top | |
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| Make Sense of top Output | |
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| Diagnose High User Time | |
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| Diagnose Out-of-Memory Issues | |
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| Diagnose High I/O Wait | |
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| Troubleshoot High Load after the Fact | |
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| Configure sysstat | |
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| View CPU Statistics | |
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| View RAM Statistics | |
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| View Disk Statistics | |
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| View Statistics from Previous Days | |
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| Why Won't the System Boot? Solving Boot Problems | |
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| The Linux Boot Process | |
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| The BIOS | |
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| GRUB and Linux Boot Loaders | |
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| The Kernel and Initrd | |
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| /sbin/init | |
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| BIOS Boot Order | |
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| Fix GRUB | |
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| No GRUB Prompt | |
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| Stage 1.5 GRUB Prompt | |
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| Misconfigured GRUB Prompt | |
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| Repair GRUB from the Live System | |
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| Repair GRUB with a Rescue Disk | |
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| Disable Splash Screens | |
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| Can't Mount the Root File System | |
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| The Root Kernel Argument | |
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| The Root Device Changed | |
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| The Root Partition Is Corrupt or Failed | |
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| Can't Mount Secondary File Systems | |
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| Why Can't I Write to the Disk? Solving Full or Corrupt Disk Issues | |
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| When the Disk Is Full | |
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| Reserved Blocks | |
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| Track Down the Largest Directories | |
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| Out of Inodes | |
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| The File System Is Read-Only | |
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| Repair Corrupted File Systems | |
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| Repair Software RAID | |
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| Is the Server Down? Tracking Down the Source of Network Problems | |
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| Server A Can't Talk to Server B | |
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| Client or Server Problem | |
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| Is It Plugged In? | |
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| Is the Interface Up? | |
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| Is It on the Local Network? | |
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| Is DNS Working? | |
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| Can I Route to the Remote Host? | |
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| Is the Remote Port Open? | |
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| Test the Remote Host Locally | |
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| Troubleshoot Slow Networks | |
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| DNS Issues | |
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| Find the Network Slowdown with traceroute | |
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| Find What Is Using Your Bandwidth with iftop | |
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| Packet Captures | |
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| Use the tcpdump Tool | |
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| Use Wireshark | |
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| Why Won't the Hostnames Resolve? Solving DNS Server Issues | |
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| DNS Client Troubleshooting | |
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| No Name Server Configured or Inaccessible Name Server | |
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| Missing Search Path or Name Server Problem | |
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| DNS Server Troubleshooting | |
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| Understanding dig Output | |
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| Trace a DNS Query | |
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| Recursive Name Server Problems | |
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| When Updates Don't Take | |
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| Why Didn't My Email Go Through? Tracing Email Problems | |
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| Trace an Email Request | |
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| Understand Email Headers | |
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| Problems Sending Email | |
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| Client Can't Communicate with the Outbound Mail Server | |
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| Outbound Mail Server Won't Allow Relay | |
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| Outbound Mail Server Can't Communicate, with the Destination | |
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| Problems Receiving Email | |
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| Telnet Test Can't Connect | |
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| Telnet Can Connect, but the Message Is Rejected | |
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| Pore Through the Mail Logs | |
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| Is the Website Down? Tracking Down Web Server Problems | |
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| Is the Server Running? | |
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| Is the Remote Port Open? | |
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| Test the Remote Host Locally | |
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| Test a Web Server from the Command Line | |
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| Test Web Servers with Curl | |
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| Test Web Servers with Telnet | |
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| HTTP Status Codes | |
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| 1xx Informational Codes | |
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| 2xx Successful Codes | |
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| 3xx Redirection Codes | |
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| 4xx Client Error Codes | |
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| 5xx Server Error Codes | |
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| Parse Web Server Logs | |
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| Get Web Server Statistics | |
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| Solve Common Web Server Problems | |
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| Configuration Problems | |
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| Permissions Problems | |
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| Sluggish or Unavailable Web Server | |
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| Why Is the Database Slow? Tracking Down Database Problems | |
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| Search Database Logs | |
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| MySQL | |
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| PostgresSQL | |
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| Is me Database Running? | |
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| MySQL | |
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| PostgresSQL | |
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| Get Database Metrics | |
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| MySQL | |
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| PostgresSQL | |
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| Identify Slow Queries | |
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| MySQL | |
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| PostgresSQL | |
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| It's the Hardware's Fault! Diagnosing Common Hardware Problems | |
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| The Hard Drive Is Dying | |
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| Test RAM for Errors | |
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| Network Card Failures | |
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| The Server Is Too Hot | |
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| Power Supply Failures | |
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| Index | |