This article explains noteworthy differences and improvements between CentOS 6 and CentOS 7 to help in deciding which version to use.

What is CentOS 7?

CentOS 7 is the most recent major release of the CentOS Linux distribution.  It is based on Red Hat Enterprise Linux 7, which is derived from Fedora Linux version 19.  It was first released on July 7th, 2014 and will be supported for 10 years, up through June 30th, 2024.

What's New in CentOS 7?

CentOS 7 includes several major changes that pertain to booting up and managing the system.  It is the first to introduce "systemd" which controls how services are started up, as well as many system settings.  It also includes "firewalld" as a new method of managing the server's firewall.

CentOS 7 also provides updates most common hosting software.  The following table lists the differing versions of commonly-used components between CentOS 5, 6, and 7.

Compatibility

The system has been designed to be backward-compatible with old methods of managing hardware and services, so older software will usually continue to function correctly, even though it cannot take advantage of any new system features.

MySQL has been replaced with MariaDB.  The two database servers are compatible and function the same way.  If your application works with MySQL 5.5, it should have no trouble working with MariaDB 5.5 and shouldn't notice the difference.

In most cases, newer software versions are backward compatible with old applications.  If in doubt, you should check with your application vendor to ensure there are no compatibility issues with CentOS 7 or the newer software it provides.

Should I Choose CentOS 7?

We recommend choosing CentOS 7 for new deployments unless there's a specific reason to avoid it.  Using CentOS 7 has the following advantages:

• As the newest release of CentOS, it will be supported for the longest period of time. Security and major bug fixes will be provided until 2024.
• All software that Steadfast supports with CentOS 6 is known to work well with CentOS 7.
• It includes new features and optimizations that will never be included in previous CentOS releases.
• It boots faster and runs better on most newer hardware than previous CentOS releases.
• Applications will soon begin to discontinue support for older releases in order to take advantage of new technology.

CentOS 6 still remains the better choice in the short term in some specific cases:

• You have applications or scripts that you know are not compatible with systemd, or with one of the new software versions listed in the table above.
• You have an existing cluster of servers and would like to maintain the same software configurations across the entire environment.
• You are using very old legacy hardware which CentOS 7 doesn't support.  If this is the case, we encourage you to consider upgrading to a newer server.

In mid-2017, CentOS 6 will stop being revised for new types of hardware, after which it will become increasing likely that some Steadfast products will no longer be compatible.  If you build an environment based on version CentOS 6 now, you may have trouble expanding it in the future without having to mix different versions of CentOS.

Getting Advice

If you aren't sure which version of CentOS to select or you need any other help finding the right solution for your environment, contact us, and we'll be happy to help!