Over the past two years, the CentOS project, a community Linux distribution based on and binary compatible with Red Hat, has undergone continuous changes. As with other free software projects, this popular (and stable) distribution, used by companies and organizations around the world, became a “development version” of Red Hat Enterprise Linux. The same goes for oVirt vs RHEV or Foreman + Katello vs Satellite. In return, Red Hat offers free licenses for small deployments and has expanded educational subscription options.
What happens with CentOS Stream?
It is not that CentOS Stream is no longer stable, or that its users unwittingly become beta-testers . of Red Hat Enterprise, but fundamental aspects were changed. Until now, when Red Hat released version X, a few months later, the same versions of the same packages were compiled, creating a “clone” with the same functionality for those who did not need enterprise-level support. This is no longer the case (updates and changes become more frequent) and, all over the world, users are wondering what to do. CERN in Switzerland, for example, has decided to stay with CentOS Stream for the time being. Perhaps because it is better the devil you know than the devil you don’t… but that’s another story.
In parallel, Ubuntu, Red Hat and SUSE offer all their repositories for x86 but also for ARM and ppc64le (Linux on IBM Power), so we were very interested in testing if these new CentOS heir distributions were being compiled for these architectures and if we could migrate to them from CentOS Stream. If so, we believe it could be a good incentive for customers who have (or are considering acquiring) IBM Power servers to give this technology a chance, which, if deployed successfully, not only achieves much better performance per core, but also greatly reduces licensing costs and the hours required for technical maintenance.
Alma vs CentOS, Rocky and Oracle Linux
In this table we have the distributions based on Red Hat that we can (or will) install on IBM Power, and their fundamental characteristics.
| Benchmarking against RHEL | AlmaLinux | Oracle Linux | Rocky Linux | CentOS Stream | CentOS Linux |
| Available from | March 2021 | 2006 | June 2021 | 2019 | 2004 |
| 1:1 binary compatibility with RHEL | Yes | Nearly * (changes in glibc, openssl…) | Yes | ACG limits apply. | Yes |
| Updates every | Daily | Daily | Daily | RHEL Upstream | Daily |
| Life Cycle | 10 Years | 10 Years | 10 Years | 5 Years | EOL on 2021-12-31 |
| Commercial support | Third parties | Oracle, third parties | Third parties | Third parties | Third parties |
| PowerPC support | Yes | Yes | Not yet | Yes | Yes |
| Support for s390x | Not yet | To be decided | To be decided | Yes | Yes |
| Property of: | AlmaLinux OS Foundation | Oracle Inc | Rocky Enterprise Software Foundation | Red Hat Inc | Red Hat Inc |
| Type of owner’s organization | Non-Profit 501(c)6 | For Profit C-Corp | For Profit, Public Benefit Corp | For Profit C-Corp | For Profit C-Corp |
As you can see, if we are looking for an alternative to CentOS Linux for Power, AlmaLinux seems to be the most interesting option and with 10 years of updates in each version.
Testing AlmaLinux (ppc64le)
In order to write this article we have done two types of tests. The first one was to install AlmaLinux from the AlmaLinux DVD on a Power8 server. As you can see, beyond booting from the LPAR SMS, the installation is the same as on an x86 system.
What if we want to migrate from CentOS Stream to AlmaLinux?
There is a script that you can download here, which we downloaded in a second environment with a freshly updated CentOS Stream.
$ wget https://raw.githubusercontent.com/AlmaLinux/almalinux-deploy/master/almalinux-deploy.sh
It is necessary to edit this script before executing it
$ vi almalinux-deploy.sh
And modify the next line, where it verifies the architecture because ppc64le IS SUPPORTED and we have all the software packages available (we are going to check it).
Next we run the script, which you will probably need to launch with the -d option to downgrade from the current version of CentOS Stream to AlmaLinux 8.X (it will always be somewhat older than the latest CentOS Stream).
And then you can install epel-release and the rest of the repositories with additional software as you would in any x86 environment.
Being an IBM Power environment, it is advisable to install the software packages that add functionality (based on AIX commands) to be able to correctly manage all the HW, access the HMC console and be able to make configuration changes without rebooting the systems.
$ yum install wget
$ wget ftp://public.dhe.ibm.com/software/server/POWER/Linux/yum/download/ibm-power-repo-latest.noarch.rpm
$ rpm -ivh –nodeps ibm-power-repo-latest.noarch.rpm
Here, once again, you have to edit the configuration script to make it work in AlmaLinux. You will see that there is an exit 1 if it is not centos/suse/redhat that we are going to modify to look like this
$ vi /opt/ibm/lop/configure
$ chmod +x /opt/ibm/lop/configure
$ /opt/ibm/lop/configure
Install the epel repository (contains a lot of additional software)
$ yum install epel-release
And we can see how the new repositories are already active
$ yum repolist
We download the PowerVM utilities for the Linux LPAR to be managed from the HMC.
$ yum install src ksh rsct.core devices.chrp.base.ServiceRM DynamicRM
And restart the RMC services (which are used to add or remove memory and cpu dynamically).
$ /usr/bin/rmcctrl -z
$ /usr/bin/rmcctrl -A
$ /usr/bin/rmcctrl -p
The final test
We are going to use a script of several lines to deploy a web server, database and a WordPress site.
$ wget https://github.com/UncleDan/linux-scripts/blob/master/wordpress-centos8.sh
$ bash wordpress-centos8.sh
We entered our IP with the browser and Wodpress worked! This is something that two years ago we could not say would work with this security. We are happy to see that a lot of progress has been made and that ppc64le application support is becoming more extensive and complete. We encourage you to try it out without the need to invest in new licenses.
What other applications and services can we deploy on Linux on IBM Power?
To finish this article we leave you a list of applications available in OpenShift for Power and that are therefore fully supported in any Red Hat based distribution, such as AlmaLinux and CentOS. What are you waiting for to try it?
Operating systems under containers (docker / runC)+ Red Hat | Middleware+ WebSphere Liberty | Languages+ Jenkins
|
Databases+ MongoDB | Analytics & AI+ Grafana | Storage+ Container Storage Interface Communications+ Prometheus |