Chapter 1. Introduction

The Migration Planning Guide documents the migration of any minor version of a Red Hat Enterprise Linux 5 installation to Red Hat Enterprise Linux 6 by highlighting key behavioral changes worthy of note when migrating.
This guide is intended to increase ease of use of Red Hat Enterprise Linux 6 by providing guidelines for changes in the product between Red Hat Enterprise Linux 5 and Red Hat Enterprise Linux 6. This guide is however not designed to explain all new features: it is focused on changes to the behavior of applications or components which were part of Red Hat Enterprise Linux 5 and have changed in Red Hat Enterprise Linux 6 or whose functionality has been superseded by another package.

1.1. Red Hat Enterprise Linux 6

Red Hat Enterprise Linux is the leading platform for open source computing. It is sold by subscription, delivers continuous value and is certified by top enterprise hardware and software vendors. From the desktop to the datacenter, Red Hat Enterprise Linux couples the innovation of open source technology and the stability of a true enterprise-class platform.
Red Hat Enterprise Linux 6 is the next generation of Red Hat's comprehensive suite of operating systems, designed for mission-critical enterprise computing. This release is available as a single kit on the following architectures:
  • i386
  • AMD64/Intel64
  • System z
  • IBM Power (64-bit)
In this release, Red Hat brings together improvements across the server, desktop and the overall Red Hat open source experience. The following are some of the many improvements and new features that are included in this release:
Power Management
Tickless kernel and improvements through the application stack to reduce wakeups, power consumption measurement by PowerTOP, Power Management (ASPM, ALPM), and adaptive system tuning by Tuned.
next generation Networking
Comprehensive IPv6 support (NFS 4, CIFS, mobile support [RFC 3775], ISATAP support), FCoE, iSCSI, and a new and improved mac80211 wireless stack.
Reliability, Availability, and Serviceability
System level enhancements from industry collaborations to make the most of hardware RAS capabilities and NUMA architectures.
Fine-grained Control and Management
Improved scheduler and better resource management in the kernel using Completely Fair Scheduler (CFS) and Control Groups (CG).
Scalable Filesystems
ext4 is the default filesystem, and xfs offers robustness, scalability, and high-performance.
Virtualization
KVM includes performance improvements and new features, sVirt protects the host, VMs, and data from a guest breach, SRIOV and NPIV deliver high performance virtual use of physical devices, and libvirt leverages kernel CG controller functionality.
Enterprise Security Enhancement
SELinux includes improved ease of use, application sandboxing, and significantly increased coverage of system services, while SSSD provides unified access to identity and authentication services as well as caching for off-line use.
Development and Runtime Support
SystemTap (allows instrumentation of a running kernel without recompilation), ABRT (simple collection of bug information), and improvements to GCC (version 4.4.3), glibc (version 2.11.1), and GDB (version 7.0.1).