CentOS is a popular alternative to RHEL. In this blog, we break down what CentOS is and provide an overview of CentOS Linux.
CentOS — Community Enterprise Operating System — is a Linux distribution functionally compatible with Red Hat Enterprise Linux (RHEL). In fact, CentOS is derived from RHEL.
Functional compatibility means that aside from RHEL subscription management, and RHEL branding, the two distributions are the same for a given version. Often, the two distributions are referred together as “Enterprise Linux”, or EL, for short.
A Linux distribution is a collection of software distributed with the Linux kernel. Often, Linux distributions contain the GNU toolchain. Thus, some refer to the distributions as GNU/Linux distributions.
In this sense, CentOS and RHEL are GNU/Linux distributions. That said, modern Linux distributions contain many applications beyond the kernel and the GNU toolchain.
If you have spent any time in the Linux user community, you know Linux distributions basing themselves on other distributions is common For example, one of the most popular Linux distributions, Ubuntu, is based on Debian.
The CentOS relationship to RHEL is very different from the Ubuntu relationship to Debian. It is novel within the big-name distributions.
Enterprise Linux at a Fair PriceUsing RHEL? It might be time to consider a migration to CentOS Linux. In our recent white paper, Enterprise Linux at a Fair Price, you'll learn the business case for migrating to CentOS and get the tips you need to start your journey.Get the White Paper
Using RHEL? It might be time to consider a migration to CentOS Linux. In our recent white paper, Enterprise Linux at a Fair Price, you'll learn the business case for migrating to CentOS and get the tips you need to start your journey.
Get the White Paper
Here's a quick overview of how CentOS Linux team takes the RHEL source and turns it into CentOS.
When the CentOS team removes the RHEL branding, they remove images and logos owned by Red Hat. They do not erase every instance of the term “rhel” or “Red Hat” from the distribution. For example, in the screenshot below you can see the full install of rhel-system-roles on CentOS 7. Depending on what packages you already have installed, your output may look different.
If you look at the source for the rhel-system-roles package for the most recent version, you will see that it includes, the storage role, added as a new feature in RHEL 8.1.
If you would like to learn more about the CentOS source, or get involved in the project, check out the canonical source for CentOS.
While moving from 8.0 to 8.1 is a big deal, Linux distributions are constantly receiving security fixes as vulnerabilities are discovered. The goal of the CentOS project is to have a security patch out within 72 hours of when the patch comes out in Red Hat. The CentOS FAQ notes that “normally” the patches are out within 24 hours.
There is a delay in creating CentOS from RHEL, so it's important to be mindful of CentOS Linux version numbering. You can find the latest version of CentOS in the CentOS release notes.
As of June 2020, CentOS Linux 8.2 is out. While individual patches often get included in the CentOS repos within 24 hours, on average, it takes about 42 days for a CentOS point release to follow a RHEL point release.
Red Hat released RHEL 8.2 on April 28, 2020. CentOS 8.2 released on June 15, which is an amazing achievement considering all the changes in the world due to the COVID-19 pandemic.
There are some key differences between versions of CentOS Linux distributions, including CentOS 8.
One of the major differences between CentOS 8.0 and CentOS 8.1 is that there were important changes to external kernel parameters. Some of these are new kernel parameters, so you will need an upgraded kernel to use them. Other parameters are simply changing to settings and looking at the changes that are now considered best practice could be useful if you are unable to upgrade to CentOS 8.1 at this time.
Of course, what CentOS decides is a best practice may not be the best for your environment. If you need help to determine the best kernel parameters for your environment, connect with one of our open source experts.
The other new features in CentOS 8.1 are broken into 17 categories. Some highlights include security, development tools, and virtualization. If you go through the list on the Red Hat website, you will notice something called “Red Hat Enterprise Linux System Roles”. That is the rhel-system-roles package I installed as a demo above.
On top of new features, there are also new and updated drives, technology previews, deprecated functionality, and, of course, bug fixes.
CentOS 6 EOL is coming, and it's important to make a plan now if you're still using CentOS 6.
CentOS Linux is a great alternative to RHEL. If you're looking to migrate to CentOS — or if you're already on CentOS but need help — the OpenLogic CentOS experts are here.
OpenLogic offers similar support for CentOS that Red Hat provides for RHEL. But, when you choose CentOS with OpenLogic support, you can achieve huge cost-savings.
You'll get the benefits of adopting a truly open source model:
But you'll be backed by the support of the OpenLogic team, reducing risk and ensuring security for your business.
With OpenLogic's CentOS Linux support, you'll get:
Find out how OpenLogic's CentOS Linux experts can help you. Get in touch today and start getting more out of enterprise Linux with CentOS.
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Doug has 18 years of experience in various technology fields. He was previously head of the Madison Linux User Group and the Carolina Open Source Initiative. He has broad experience, having worked in government, healthcare, enterprise, and start-ups.