Choosing between CentOS 7 & RHEL 7
Find out the differences between CentOS 7 and RHEL 7 operating systems. We prepared a review for both commonly used operating systems – RHEL and CentOS. Check out their features described below and choose the best option for you.
Red Hat Enterprise Linux a.k.a. RHEL is Red Hat’s official distribution. All of the Red Hat support services, SLAs (Service Level Agreements), and certifications are based on RHEL.
It is intended to be an enterprise level, stable, and secure operating system. RHEL’s major versions have support cycle length of 7 years with an option to extend up to 10 years, thus being more stable and secure OS compared to (for example) Fedora, which is more of a bleeding edge Linux distro.
It is known that Red Hat Enterprise Linux is open source. Therefore, the code is available for Red Hat users, yet it is not free to use.
CentOS is a community-developed and supported alternative to RHEL. It is similar to Red Hat Enterprise Linux but lacks the enterprise-level support. CentOS is more or less a free replacement for RHEL with few minor configuration differences.
It comes with extended support lifecycle ranging from 6 to 7 years. Latest major CentOS version 7 will be supported till 2020!
CentOS does tend to run a little behind RHEL with releases. Minor releases can take hours or days to be deployed and for major releases, it can be several months. It might seem like an insignificant disadvantage, having in mind that you get CentOS for free, but for companies that think in terms of multiple year lifespans for their servers and software, the difference can be trivial.
What to choose?
While choosing between CentOS and RHEL you might be confused what is the better option for you… Should you invest your money and opt-in for an enterprise-grade distribution, or will you be paying for support which you do not need and CentOS is just enough?
Let’s dig a little deeper
Why would you choose RHEL? Well, the main reason to go for RHEL on your server is if you need an extremely stable and secure distribution with enterprise level support and SLAs offered by Red Hat. As you might imagine, Red Hat’s support services are not free and cost a few hundred dollars up to thousands of dollars.
On the other hand, if you need enterprise-level distribution without the cost of Red Hat’s support package, then there is CentOS waiting for you as the best option!
RHEL 7 features
XFS as a default
RHEL7 is using XFS as the default filesystem. XFS was created by Silicon Graphics International and has been in production to use with Linux systems for a long time now. On RHEL 7 it will support file systems up to 500TB in size.
Interesting fact: NASA Advanced Supercomputing Division is using XFS, and takes advantage of it by deploying two 300TB+ filesystems on two SGI Altix archival storage servers. Each of the two are attached to multiple Fibre Channel disk arrays!
Systemd process manager
Adoption of systemd has replaced init – the old Unix way of starting processes and services on the system. RHEL did not rush with implementing systemd.
Systemd was introduced in Fedora v15 in 2010, thus giving Red Hat useful information how it functions in the real world. Apart from being the new default way of starting Linux systems, systemd also incorporates performance profiles, tuning, optimized performance and is easily scalable.
Docker is a popular app virtualization technology. Apps that are packed by Docker are isolated from the system and each other. They can be moved between systems and still run independently.
The long-term idea of Docker implementation in RHEL involves possibly breaking the operating system itself into containers. This would allow system deployment with minimal overhead.
Originally created by Silicon Graphics International, PCP (Performance Co-Pilot) is now available as part of RHEL 7 release.
Not only it lets the users monitor and record system statistics but with APIs and a tool set it makes that data available to other subsystems like the new systemd process manager.
Another aspect of PCP is new performance profiles. Although RHEL 6 already had performance profiles, so that users could tune RHEL to meet specific usage scenarios, RHEL 7 is doing it just a tad bit better. RHEL 7 now defaults to a new profile that emphasizes maximum performance and also includes another new default profile to balance performance with energy saving.
CentOS 7 features
A lot of the features in CentOS are coming from RHEL – such as systemd, Docker, XFS, etc., however, CentOS has its own features that differ from RHEL 7.
Before CentOS 7, upgrading major point releases required reinstallation of the whole OS. Now it supports an upgrade path from CentOS 6 to CentOS 7.
Note: If you are using an older version of CentOS, you will not be able to upgrade directly.
In CentOS 7, MySQL was switched with MariaDB. For those, who do not know what MariaDB is – it is a community developed MySQL replacement.
This change was made when Oracle bought out MySQL but the community wanted to keep it open source. MariaDB works and acts exactly as MySQL thus being a drop-in replacement.
Linux has largely moved to systems with 64-bit processing. Only 64-bit kernels and ISOs are available with the latest version.
Oh, did I mention? This also originally comes from RHEL (and is also one of RHEL 7 features) and is implemented to CentOS 7 as it is a derivative of RHEL.
Worried about 32-bit applications? Fear not! 32-bit libraries allow users to run 32-bit applications.
This review might have given you a slight overview of what is new in RHEL and CentOS. We can say one thing for sure – both distros are similar while also differ from each other when it all comes down to decision making what you need and want to use.
Go for RHEL if you need professional Red Hat support. On the other hand, if you are an expert with Linux operating systems and you need a stable distro without the pricey support services, opt-in for a CentOS 7 distribution.
You definitely will not be disappointed!