RHEL 8 New Features for Experienced Linux Administrators
Abstract
| Goal | Install RHEL 8 or upgrade an existing system from RHEL 7 to RHEL 8. |
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Objectives
After completing this section, students should be able to install RHEL 8 on a new server.
Repository Structure
Red Hat Enterprise Linux has changed the way packages are divided into channels or repositories. Packages are reorganized into Base Operating System (BaseOS) and Application Stream (AppStream) repositories. Special purpose repositories are also restructured to support the new AppStream and modular contexts.
RHEL 8 Repositories and Contents
BaseOS: packages required for a minimal operating system installation.
AppStream: most other packages, except those requiring add-on entitlements.
CodeReady Linux Builder: packages providing programming language build-time dependencies; used by application developers.
The Extras and Optional repositories have been removed. AppStream design makes additional repositories unnecessary. Packages were moved to AppStream or dropped. Appropriate dropped packages might end up in EPEL.
Supplemental: exists and retains the same role in RHEL 8.
There are add-on repositories for High Availability, Resilient Storage, Real Time, and Real Time for NFV. Add-on products require additional entitlements.
Installation Media Structure
The installation media choices determine the method for initiating an installation. The media choices remain the same as in previous RHEL versions. The repository changes determine from where packages are installed. The modularity of AppStream changes how packages are grouped and layered on the Base OS.
Available Installation Media Formats
Netboot ISO: contains only the Anaconda installer. This method requires a configured network to access package repositories available by HTTP, FTP, or NFS.
Binary DVD: contains Anaconda, and both the BaseOS and AppStream repositories.
QCOW2 image: prebuilt system disk ready to deploy as a VM in cloud or virtual environments.
Package Modularity
Red Hat Enterprise Linux 8 brings some additions in package management capabilities.
Modules
Yum uses a new package grouping method called modules. A module is a set of RPM packages that form an application profile.
Module Features
Modules can be installed independently of the underlying Operating System major version.
The module system design supports multiple application versions simultaneously.
Modules can contain several streams to make multiple application versions available for installation.
A stream represents an application version substantially different from previous versions.
A stream may be created when a newer application version is not backward compatible.
Installing a stream wholly replaces the previously installed stream, whether as an upgrade or downgrade. Contrast this with a legacy package upgrade which adds or removes only changed package files.
For example, you could install the Perl 5.24 stream, and even though Perl 5.26 packages are available, no updates will be listed or applied. You could switch to the Perl 5.26 stream at any time. The module feature replaces Red Hat Software Collections.
The full module naming specification takes the form name:stream:version:context:architecture/profile.
Shorter specifications can be used when the default values are acceptable.
Module Naming Specification
namename:streamname:stream:versionAny of the above specifications with ::
architectureappended.name:stream:version:context:architectureAny of the above specifications with /
profileappended.
Describing the System Purpose Configuration
The System Purpose configuration dialog box is a new installation feature that allocates accurate system entitlements to match the intended system use.
System Purpose Dialog Box
Role: choice of server, workstation, compute node, or client.Service Level Agreement: the level of support this system needs.Usage: choice of production, development, or disaster recovery.These choices determine how subscription attachments and entitlement consumption are handled during installation.
System Purpose Kickstart Directives
syspurpose --role=
syspurpose --sla=
syspurpose --usage=
References
For more information, refer to the Performing a standard RHEL installation guide at https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html-single/performing_a_standard_rhel_installation
