Chapter 3. Changes to packages, functionality, and support

Read this chapter for information about changes to the functionality or to packages provided in Red Hat Enterprise Linux 7, and changes to the support of said packages.

3.1. New Packages

This section describes notable packages now available in Red Hat Enterprise Linux 7.

3.1.1. Preupgrade Assistant

The Preupgrade Assistant (preupg) checks for potential problems you might encounter with an upgrade from Red Hat Enterprise Linux 6 to Red Hat Enterprise Linux 7 before making any changes to your system. This helps you assess your chances of successfully upgrading to Red Hat Enterprise Linux 7 before the actual upgrade process begins.
The Preupgrade Assistant assesses the system for possible in-place upgrade limitations, such as package removals, incompatible obsoletes, name changes, deficiencies in some configuration file compatibilities, and so on. It then provides the following:
  • System analysis report with proposed solutions for any detected migration issues.
  • Data that could be used for "cloning" the system, if the in-place upgrade is not suitable.
  • Post-upgrade scripts to finish more complex issues after the in-place upgrade.
Your system remains unchanged except for the information and logs stored by the Preupgrade Assistant.
For detailed instructions on how to obtain and use the Preupgrade Assistant, see Section 1.1.3, “Check system upgrade suitability”.

3.1.2. Red Hat Upgrade Tool

The new Red Hat Upgrade Tool is used after the Preupgrade Assistant, and handles the three phases of the upgrade process:
  • Red Hat Upgrade Tool fetches packages and an upgrade image from a disk or server, prepares the system for the upgrade, and reboots the system.
  • The rebooted system detects that upgrade packages are available and uses systemd and yum to upgrade packages on the system.
  • Red Hat Upgrade Tool cleans up after the upgrade and reboots the system into the upgraded operating system.
Both network and disk based upgrades are supported. For detailed instructions on how to upgrade your system, see Chapter 1, How to Upgrade.

3.1.3. Chrony

Chrony is a new NTP client provided in the chrony package. It replaces the reference implementation (ntp) as the default NTP implementation in Red Hat Enterprise Linux 7. However, it does not support all features available in ntp, so ntp is still provided for compatibility reasons. If you require ntp, you must explicitly remove chrony and install ntp instead.
Chrony's timekeeping algorithms have several advantages over the ntp implementation.
  • Faster, more accurate synchronization.
  • Larger range for frequency correction.
  • Better response to rapid changes in clock frequency.
  • No clock stepping after initial synchronization.
  • Works well with an intermittent network connection.
For more information about chrony, see the Red Hat Enterprise Linux 7 System Administrators Guide or System Administrators Reference Guide, available from http://access.redhat.com/site/documentation/Red_Hat_Enterprise_Linux/.

3.1.4. HAProxy

HAProxy is a TCP/HTTP reverse proxy that is well-suited to high availability environments. It requires few resources, and its event-driven architecture allows it to easily handle thousands of simultaneous connections on hundreds of instances without risking the stability of the system.
For more information about HAProxy, see the man page, or consult the documentation installed along with the haproxy package in the /usr/share/doc/haproxy directory.

3.1.5. Kernel-tools

The kernel-tools package includes a number of tools for the Linux kernel. Some tools in this package replace tools previously available in other packages. See Section 3.3, “Deprecated Packages” and Section 3.2, “Package Replacements” for details.

3.1.6. NFQUEUE (libnetfilter_queue)

Red Hat Enterprise Linux 7.1 provides the libnetfilter_queue package. This library enables the NFQUEUE iptables target, which specifies that a listening user-space application will retrieve a packet from a specified queue and determine how that packet will be handled.

3.1.7. SCAP Security Guide

The scap-security-guide package provides security guidance, baselines, and associated validation mechanisms for the ​Security Content Automation Protocol (SCAP). Previously, this package was only available through the EPEL repository (Extra Packages for Enterprise Linux). As of Red Hat Enterprise Linux 7.1, scap-security-guide is available in the Red Hat Enterprise Linux 7 Server (RPMS) repository.

3.1.8. Red Hat Access GUI

Red Hat Access GUI is a desktop application, which lets you find help, answers, and utilize diagnostic services using Red Hat Knowledgebase, resources, and functionality. If you have an active account on the Red Hat Customer Portal, you can access additional information and tips of the Knowledgebase easily browsable by keywords. Red Hat Access GUI is already installed if you select to have the GNOME Desktop installed.
For more information on the benefits, installation, and usage of this tool, see Red Hat Access GUI.