Fresh install CentOS 8.4 from within CentOS 8.5

centoscentos8installation

Prehistory
I had CentOS 8.4 4.18.0-305.3.1 installed.
Everything was good until I run yum -y update without understanding what it means.
After that CentOS get upgraded to 8.5 4.18.0-348.2.1 version, which is not suitable for my purposes.

I have tried naive attempts to get OS version back to 8.4 4.18.0-305.3.1:

yum history undo. 
switching to kernel version 4.18.0-305.3.1. 
yum downgrade redhat-release

But nothing helped.

Is it possible to mount to the existing machine ISO with OS version I need, boot from that ISO and install CentOS 8.4 4.18.0-305.3.1 over existing OS 8.5?

Best Answer

Staying on CentOS 8.4 is not responsible patching policy.

  • CentOS does not have extended update support for minor versions like RHEL does. You will not get security and other fixes.
  • CentOS Linux 8 ends at the end of 2021, the future is Stream. (Red Hat didn't have the courage to cut over to Stream prior to 8, long story.) Updates will stop and you will not see 8.6.

Decide if you wish to use CentOS Stream or some other RHEL build.

Switching from CentOS 8 to 8 Stream is a matter of swapping the release repos and dnf distro-sync

Or, switch to Alma, Rocky, RHEL, or Oracle EL with the tools they recommend.

Get the latest version into an usable state, whatever that means. You might be testing applications, repackaging or rebuilding software, or filing issues so other people can help with getting it working on updated RHEL.

I deferred avoided talking about recovering your CentOS 8.4 because it is an option that will take some work. Anaconda installer will not downgrade the existing install for you. Attempt dnf history rollback to revert to prior to the big update. Unfortunately, that may be a difficult transaction to complete. You may wish to reinstall new copy of the OS on the desired version and restore data. And review all the updates you are deferring. Come up with a plan to mitigate what they fix in some other way, such as building your own packages, or doing other security controls.

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