Red Hat Enterprise Linux 9

Release Notes


Important planning recommendations and guidance to review before deploying.

Considerations in adopting RHEL 9

Key differences between RHEL 8 and RHEL 9

Getting the most from your Support experience

Gathering troubleshooting information from RHEL servers with the sos utility

Package manifest

Package listing for Red Hat Enterprise Linux 9

Installing RHEL

Interactively installing RHEL from installation media

Installing RHEL on a local system using the graphical installer

Interactively installing RHEL over the network

Installing RHEL on several systems using network resources or on a headless system with the graphical installer

Automatically installing RHEL

Deploying RHEL on one or more systems from a predefined configuration

Boot options for RHEL Installer

Customizing the installation program's behavior by specifying boot options

Customizing Anaconda

Changing the installer appearance and creating custom add-ons on Red Hat Enterprise Linux

Upgrading RHEL

Upgrading from RHEL 8 to RHEL 9

Instructions for an in-place upgrade from Red Hat Enterprise Linux 8 to Red Hat Enterprise Linux 9

Composing RHEL images using Image Builder

Composing a customized RHEL system image

Creating customized system images with RHEL image builder on Red Hat Enterprise Linux 9

Composing, installing, and managing RHEL for Edge images

Creating, deploying, and managing Edge systems with Red Hat Enterprise Linux 9

System Administration

Deployment, administration, and tuning

Configuring basic system settings

Set up the essential functions of your system and customize your system environment

Managing systems using the RHEL 9 web console

Server management with a graphical web-based interface

Configuring and using a CUPS printing server

Configure your system to operate as a CUPS server and manage printers, print queues and your printing environment

Managing software with the DNF tool

Managing content in the RPM repositories by using the DNF software management tool

Automating system administration by using RHEL system roles

Consistent and repeatable configuration of RHEL deployments across multiple hosts with Red Hat Ansible Automation Platform playbooks

Managing networking infrastructure services

A guide to managing networking infrastructure services in Red Hat Enterprise Linux 9

Deploying mail servers

Configuring and maintaining mail server services

Deploying web servers and reverse proxies

Setting up and configuring web servers and reverse proxies in Red Hat Enterprise Linux 9

Installing and using dynamic programming languages

Installing and using Python and PHP in Red Hat Enterprise Linux 9

Configuring and using database servers

Installing, configuring, backing up and migrating data on database servers

Managing, monitoring, and updating the kernel

A guide to managing the Linux kernel on Red Hat Enterprise Linux 9

Monitoring and managing system status and performance

Optimizing system throughput, latency, and power consumption

Getting started with the GNOME desktop environment

Getting started with the GNOME desktop environment on Red Hat Enterprise Linux 9

Administering the system using the GNOME desktop environment

Administering Red Hat Enterprise Linux 9 using the GNOME desktop environment

Customizing the GNOME desktop environment

Customizing the GNOME desktop environment on Red Hat Enterprise Linux 9

Using systemd unit files to customize and optimize your system

Optimize system performance and extend configuration with systemd



Managing and monitoring security updates

Update RHEL 9 system security to prevent attackers from exploiting known flaws

Security hardening

Enhancing security of Red Hat Enterprise Linux 9 systems

Using SELinux

Prevent users and processes from performing unauthorized interactions with files and devices by using Security-Enhanced Linux (SELinux)

Securing networks

Configuring secured networks and network communication

Configuring firewalls and packet filters

Managing the firewalld service, the nftables framework, and XDP packet filtering features


Configuring and managing networking

Managing network interfaces and advanced networking features

Configuring InfiniBand and RDMA networks

Configuring and managing high-speed network protocols and RDMA hardware

Identity Management

Identity management and policy

Migrating to Identity Management on RHEL 9

Upgrading a RHEL 8 IdM environment to RHEL 9 and migrating external LDAP solutions to IdM

Planning Identity Management

Planning the infrastructure and service integration of an IdM environment

Installing Identity Management

Methods of installing IdM servers and clients

Using Ansible to install and manage Identity Management

Using Ansible to maintain an IdM environment

Installing trust between IdM and AD

Managing a cross-forest trust between an IdM and AD domain

Accessing Identity Management services

Logging in to IdM and managing its services

Managing smart card authentication

Configuring and using smart card authentication

Integrating RHEL systems directly with Windows Active Directory

Joining RHEL hosts to AD and accessing resources in AD

Configuring authentication and authorization in RHEL

Using SSSD, authselect, and sssctl to configure authentication and authorization

Managing IdM users, groups, hosts, and access control rules

Configuring users and hosts, managing them in groups, and controlling access with host-based and role-based access control rules

Managing certificates in IdM

Issuing certificates, configuring certificate-based authentication, and controlling certificate validity

Managing replication in Identity Management

Preparing and verifying replication environments

Working with vaults in Identity Management

Storing and managing sensitive data in IdM

Working with DNS in Identity Management

Managing the IdM-integrated DNS service

Using external Red Hat utilities with Identity Management

Integrating services and Red Hat products in IdM

Using IdM API

Using IdM API with Python scripts

Using IdM Healthcheck to monitor your IdM environment

Performing status and health checks

Tuning performance in Identity Management

Optimizing the IdM services, such as Directory Server, KDC, and SSSD, for better performance

Preparing for disaster recovery with Identity Management

Mitigating the effects of server and data loss scenarios in IdM environments

Performing disaster recovery with Identity Management

Recovering IdM after a server or data loss


Storage and file systems

Managing file systems

Creating, modifying, and administering file systems in Red Hat Enterprise Linux 9

Configuring and using network file services

A guide to configuring and using network file services in Red Hat Enterprise Linux 9.

Managing storage devices

Configuring and managing local and remote storage devices

Configuring and managing logical volumes

Configuring and managing the LVM on RHEL

Configuring device mapper multipath

Configuring and managing the Device Mapper Multipath feature

Deduplicating and compressing logical volumes on RHEL

Deploying VDO on LVM to increase the storage capacity


Configuring GFS2 file systems

Planning, administering, troubleshooting, and configuring GFS2 file systems in a high availability cluster

Configuring and managing high availability clusters

Using the Red Hat High Availability Add-On to create and maintain Pacemaker clusters

Containers and Virtual Machines

Building, running, and managing containers

Using Podman, Buildah, and Skopeo on Red Hat Enterprise Linux 9

Configuring and managing virtualization

Setting up your host, creating and administering virtual machines, and understanding virtualization features

Using image mode for RHEL to build, deploy, and manage operating systems

Using RHEL bootable container images on Red Hat Enterprise Linux 9


Configuring and managing cloud-init for RHEL 9

Using cloud-init to automate the initialization of cloud instances

Deploying RHEL 9 on Amazon Web Services

Obtaining RHEL system images and creating RHEL instances on AWS

Deploying RHEL 9 on Google Cloud Platform

Obtaining RHEL system images and creating RHEL instances on GCP

Deploying RHEL 9 on Microsoft Azure

Obtaining RHEL system images and creating RHEL instances on Azure

Configuring a Red Hat High Availability cluster on Red Hat OpenStack Platform

Installing and configuring HA clusters and cluster resources on RHOSP instances

Developing applications

Developing C and C++ applications in RHEL 9

Setting up a developer workstation, and developing and debugging C and C++ applications in Red Hat Enterprise Linux 9

Installing, updating, and configuring OpenJDK on RHEL 9

Introduction to Java application development in RHEL 9

Developing .NET applications in RHEL 9

Installing and running .NET 6 for developing .NET applications in Red Hat Enterprise Linux 9

Packaging and distributing software

Packaging software by using the RPM package management system

Red Hat Insights for RHEL

Get Started with Red Hat Insights

Guidance for installing Insights on RHEL systems

Product Documentation for Red Hat Insights

Release Notes, user guides, and API reference documentation

RHEL for SAP Solutions

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