RHEL 8 is running on kernel version 4.18 and based on Fedora 28. Control Group V2 is supported that manages and distributes system resources in a better way compared to the previous version. Control group v2 has only single hierarchy that categorizes processes based on the role of the owner thereby removes the conflicts policies arising due to multiple hierarchies.
Enhancement in sosreport and kdump is also done. RHEL 8 now supports early kdump compared to previous versions in which kdump was not able to capture crash information early. eBPF based programs and maps can be reported using sosreport.
Support for 5-level paging now enables RHEL 8 to supports upto 4 PB of physical memory. Earlier version RHEL 7 has 4 level paging that allows addressing space of 256 TiB, same has been increased to 128 PiB and thus increasing physical address space up to 4 Pib
RHEL 8 offers improvement for package management tool yum, which is now based on DNF (Dandified Yum) technology that is advanced and has better performance with support for modular content. RPM version 4.14 is distributed in RHEL 8 and rpm now validates the package content before starting the installation. Support for packaging files above 4GB in size is added.
dnf utility allows to install, upgrade packages.
# dnf install # dnf update # dnf upgrade # dnf provides
File Systems and storage
XFS file system supports shared copy-on-write data extent functionality that allows sharing a common set of data block for two or more files that is Fast and space efficient. LUKS2 replaces the legacy LUKS1 format. LUKS2 provides encrypted volumes that supports auto recovery in case of metadata corruptions.
Stratis is new local storage manager that provides managed file systems on top of pools of storage that simplifies tasks like Managing snapshots, expanding file systems on the fly, XFS is default file system used by stratis.
RHEL 8 is having pre-installed cockpit packages on non minimal installations as well as firewall ports are opened, Package can be obtained from RHEL default repositories for minimal installations. Cockpit’s web interface can be used for managing machines remotely easily.
Cockpit is now compatible with mobile browsers, thus managing systems using mobile devices is possible now. Cockpit’s page now warns and informs about missing updates and subscriptions. Cockpit interface can also be used to apply Policy-based Decryption rules to disks on the systems.
Virtual Machines can now be created and managed using Cockpit. Another enhancement is that Networking page allows modification of firewall rules.
Replacement of nfsnobody user with nobody
nfsnobody and nobody user of RHEL 7 with ID of 65534 and 99 respectively have been merged as single user nobody with ID 65534 and RHEL 8 installation no more creates nfsnobody user.
Databases, webservers, languages
- Databases Servers in RHEL 8: MySQL 8.0, MariaDB 10.3, PostgreSQL 9.6 and PostgreSQL 10, Redis 4
- Python 3 .6 is distributed on RHEL 8
- Ruby 2.5
- PHP 7.2
- Perl 5.26
- Apache HTTP Server 2.4.35
- RHEL 8 comes with nginx 1.14 available in the base repository
RHEL 8 Desktop Environment has been rebased to GNOME 3.28 that include new features like on screen keyboard, extended device support. Wayland replaces the X.org of previous RHEL release and is the default display server in RHEL 8 that offers advantages like improved multi-monitor support, enhanced UI scaling,
iptables has been replaced with nftables as default packet filtering framework which is the successor to iptables, arptables, and ebtables tool.
nftables has several advantages like it offers single framework for ipv4 and ipv6 protocols packet filtering. Another utility nftrace is provided that helps in debugging and tracing in the ruleset.
TCP Networking Stack version 4.16 is distributed on RHEL 8 that provides more stability and better performance.
By Default, firewalld uses nftables
Bunch of new features are added like KVM supports 5-level paging, additional crash information in case KVM guest crashes, Ceph storage is now supported as well on KVM
RHEL 8 is distributed with qemu–kvm 2.12 with new features like support for Q35 guest machine type, UEFI guest boot, vCPU hot plug/unplug, Guest I/O threading.
The openssh package have been upgraded to version 7.8p1 that removes support for ssh version 1 protocol, Enhancement in rsyslog is also there with upgraded rsylog version 8.37.0
Containers without daemons
RHEL 8 comes with Podman and buildah aka CRI-O that is alternative to dockers and can be used to manage containers.