There is a lot of roumors around since it was anounced to switch CentOS 8 from a Downstream Build from RHEL 8 to a Upstream Build for RHEL 8 on December 8th 2020.
Many people asked why a second Upstream to Fedora and the way of communication choosen was sub optimal in diplomatic words.
Cutting the support date from 31st of May 2029 to 31st of December 2021 brings many people in trouble which has upgraded their environment from CentOS 7 to CentOS 8.
CentOS 7 is supported till 30st of June 2024, so people who did not upgrade till now are fine by waiting for things happen now.
On the community side many things happens in the past 5 month, AlmalLinux 8 provided by the CloudLinux team is available as productive release 8.3 now, 8.4 is available for testing.
Rocky Linux 8, which was mainly driven by Gregory Kurtzer, one of the founders of the CentOS project in 2004, is available as Release Candidate since April 30st 2021.
Another alternative but only for small environments is RHEL 8 itself, RedHat anounced that small environments till 16 systems can be registered for free.
And Oracle Linux 8 is also a Alternative as replacement for CentOS 8.
Except RHEL 8 every Alternative can be used without registration till now.
But there is also a fair warning from my side, AlmaLinux and Rocky Linux did not support secure boot till now.
This may have consequences by company security roles, many developers did not have access to the bios to switch off secure boot.
AlmaLinux is providing a shell script to migrate existing CentOS 8 deployments to AlmaLinux:
Oracle Linux is also providing a shell script to migrate existing CentOS 8 deployments to Oracle Linux 8:
In my mind we will see the same from Rocky Linux in the near future.
Redhat has choosena different way, there is an RPM Package available for the migration but there is a need to register at RedHat, the Credentials are needed for the migration.
OK, lets start with the Installation of AlmaLinux 8, CentOS 8, oracle Linux 8, RHEL 8 and Rocky Linux 8 Release Candidate, i’m using a VMWare Environemt for this and all systems have the same ressources.
Interesting point at VMware, for Oracle Linux /RHEL 8 prefered Disk by default is NVME:
For CentOS 8 it is SCSI:
For AlmaLinux 8 or RockyLinux 8 it depends what you choose on VMWare, is your definition CentOS 8 it is SCSI, is your definition RedHat 8 it is NVME.
Installer Boot screens:
Installation Process, interesting, minimal install has a different count of packages
The installation of all 5 distributions running without issue on my VMWare environment.
One important remark, Oracle Linux is using by default the Oracle UEK Kernel and not the RHEL compatible one. So if you want to use the RHEL Compatible Kernel you need to change it afterwards.
This can have some consequences for the application you might use on these installation.
The grubby command can be used for checking and changing the default Kernel:
checking default kernel:
$ [[email protected] ~]$ grubby --default-kernel /boot/vmlinuz-5.4.17-2011.7.4.el8uek.x86_64 $ [[email protected] ~]$
switching to RHEL compatible kernel:
$ grubby --set-default /boot/vmlinuz-4.18.0-240.el8.x86_64 $ The default is /boot/loader/entries/3c1ad166c99c43adb6b61b4c980b5359-4.18.0-240.el8.x86_64.conf with index 1 and kernel /boot/vmlinuz-4.18.0-240.el8.x86_64 $ [[email protected] ~]$
Checking kernel after reboot:
$ [[email protected] ~]$ uname -r $ 4.18.0-240.el8.x86_64 $ [[email protected] ~]$ grubby --default-kernel $ /boot/vmlinuz-4.18.0-240.el8.x86_64 $ [[email protected] ~]$
With yum list kernel-uek you can list the present UEK Kernels and with yum erase kernel-uek-3.8.13-5.4.17-2011.7.4.el8uek.x86_64 the UEK Kernel can be deleted when the system is using the RHEL compatible kernel.
Another interesting Alternative can be openSUSE LEAP 15.3, that will be a Downstream Build from SLES 15.3 planned for July 2021, as i wrote in my Blog.
I did also a small test if i see any differencies by installing PostgreSQL using the method i have described in my Blog.
Or my article at heise.de.
What to do now? This is a difficult question and depends on the individual situation.
If CentOS 7 is used and there is no force by an Application to upgrade just wait and see what happens, time and community working on Alternatives like AlmaLinux or Rocky Linux or openSUSE LEAP 15.3.
If the upgrade to CentOS 8 is allready done it is a complete different situation, if there is some time left for a decision i would wait and observe what happens with AlmaLinux or Rocky Linux or openSUSE LEAP 15.3.
If there is no time left it depends on the size of the environment, less or equal to 16 systems RHEL 8 can be an Alternative to Oracle Linux or AlmaLinux.
When someone has no problems with an Upstream Build CentOS 8 Stream may be also an alternative, in any case it is a question of requirements.
One open question is secure boot, on AlmaLinux it is an open Bug/Ticket so i think it will be solved soon and hopefully we will see the same at Rocky Linux.
Secure boot requirement can have multiple reasons, company security roles, people without access to the bios to disable scure boot and so on.
As today (June 22nd) ALmaLinux and Rocky Linux are ready for production now, so for CentOS 8 replacement both can be used.