Chapter 1. Overview The Performance Tuning Guide is a comprehensive reference on the configuration and optimization of Red Hat Enterprise Linux. While this release also contains information on Red Hat Enterprise Linux 5 performance capabilities, all instructions supplied herein are specific to Red Hat Enterprise Linux 6. 1.1. How to read this book This book is divided into chapters discussing specific subsystems in Red Hat Enterprise Linux. The Performance Tuning Guide focuses on three major themes per subsystem: Features Each subsystem chapter describes performance features unique to (or implemented differently in) Red Hat Enterprise Linux 6. These chapters also discuss Red Hat Enterprise Linux 6 updates that significantly improved the performance of specific subsystems over Red Hat Enterprise Linux 5. Analysis The book also enumerates performance indicators for each specific subsystem. Typical values for these indicators are described in the context of specific services, helping you understand their significance in real-world, production systems. In addition, the Performance Tuning Guide also shows different ways of retrieving performance data (that is, profiling) for a subsystem. Note that some of the profiling tools showcased here are documented elsewhere with more detail. Configuration Perhaps the most important information in this book are instructions on how to adjust the performance of a specific subsystem in Red Hat Enterprise Linux 6. The Performance Tuning Guide explains how to fine-tune a Red Hat Enterprise Linux 6 subsystem for specific services. Keep in mind that tweaking a specific subsystem's performance may affect the performance of another, sometimes adversely. The default configuration of Red Hat Enterprise Linux 6 is optimal for most services running under moderate loads. The procedures enumerated in the Performance Tuning Guide were tested extensively by Red Hat engineers in both lab and field. However, Red Hat recommends that you properly test all planned configurations in a secure testing environment before applying it to your production servers. You should also back up all data and configuration information before you start tuning your system. 1.1.1. Audience This book is suitable for two types of readers: System/Business Analyst This book enumerates and explains Red Hat Enterprise Linux 6 performance features at a high level, providing enough information on how subsystems perform for specific workloads (both by default and when optimized). The level of detail used in describing Red Hat Enterprise Linux 6 performance features helps potential customers and sales engineers understand the suitability of this platform in providing resource-intensive services at an acceptable level. The Performance Tuning Guide also provides links to more detailed documentation on each feature whenever possible. At that detail level, readers can understand these performance features enough to form a high-level strategy in deploying and optimizing Red Hat Enterprise Linux 6. This allows readers to both develop and evaluate infrastructure proposals. This feature-focused level of documentation is suitable for readers with a high-level understanding of Linux subsystems and enterprise-level networks. System Administrator The procedures enumerated in this book are suitable for system administrators with RHCE [1] skill level (or its equivalent, that is, 3-5 years experience in deploying and managing Linux). The Performance Tuning Guide aims to provide as much detail as possible about the effects of each configuration; this means describing any performance trade-offs that may occur. The underlying skill in performance tuning lies not in knowing how to analyze and tune a subsystem. Rather, a system administrator adept at performance tuning knows how to balance and optimize a Red Hat Enterprise Linux 6 system for a specific purpose . This means also knowing which trade-offs and performance penalties are acceptable when attempting to implement a configuration designed to boost a specific subsystem's performance. [1] Red Hat Certified Engineer. For more information, refer to http://www.redhat.com/training/certifications/rhce/ .

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