CentOS 7: An Introduction

Like our series of ongoing articles on Ubuntu 14.04 LTS, we are starting a series of articles on the recently released CentOS 7 distribution. Unlike Ubuntu, new versions of CentOS take years in between major versions. CentOS also supports their major releases for quite some time (see the table below). This first post will introduce some of the major changes to CentOS at a high level and then over the next month or so, we will discuss many of these changes in more detail. Let’s get started!

CentOS Support Timeline
Just as a quick overview, let’s take a look at the support life of each of the last major releases of CentOS (in general, seven years from release date):

  • CentOS 5.x – End of Life 03/31/2017
  • CentOS 6.x – End of Life 11/30/2020
  • CentOS 7.x – End of Life 06/30/2024


In addition to these dates, note that CentOS 7 is the first version to be available in 64bit only. Since this is predominately an enterprise distribution, resources are better spent on supporting the most commonly used platform in corporate environments. Sorry to those of you still stuck using a Pentium 4!

Desktop Improvements
Although we mentioned that as an enterprise distribution, you may be more inclined to assume that you will only run these on headless servers, you will be surprised at the effort that had gone into improving the desktop experience. Previous to CentOS 7, the old and kind of tired (but eminently stable) Gnome 2.2 has been the default desktop environment. Although you could get other desktops to run (KDE), it was more trouble than it was worth and required a lot of effort. See below for the default CentOS 6 desktop appearance:

CentOS 6 Gnome 2 Desktop

In addition to the rather plain Gnome 2 Desktop Environment, getting compositing (read: 3D effects) working was also a challenge. You could always compile Compiz and all the necessary library dependencies (which was a manual process since it was not in the standard repositories until 6.4), but many of the plugins would not function. Additionally, getting the proprietary NVidia or ATI video drivers to compile could be another challenge on its own.

With CentOS 7, not only do we now have a Gnome 3 Shell Desktop Environment, we have the compositing built in (with Compiz as an option) to go along with it. Bottom line, although CentOS is not a standard desktop distribution, they have made some pretty good strides in making it a more enjoyable desktop user experience. See below for an example of the Gnome 3 Shell:

CentOS 7 Gnome 3 Shell with Compositing

The difference looks subtle in a screen shot, but certainly makes the desktop feel like something you would expect on a modern system when you are using it. Kudos to the CentOS team for spending the time to update it when it would have been easiesr to just stay with Gnome 2.

The Laundry List
So here is a quick list of some of the other major changes/updates in CentOS 7:

  1. Kernel updated to 3.10.0
  2. Open VMware Tools and 3D graphics drivers out of the box – I can confirm this works great!
  3. OpenJDK-7 as default JDK (nice upgrade but its time to give up on the OpenJDK, its just too far behind to be used in the enterprise)
  4. In Place Upgrade from 6.5 to 7.0 (this one is iffy, even in pretty vanilla installs, you can tell this is a new process for them because its full of issues, still better to bite the bullet and do a fresh install if at all possible)
  5. XFS as default file system (quite honestly I am a bit flabbergasted at this decision, we will be exploring this in a later article)
  6. iSCSI and FCoE in kernel space (iSCSI target needs work but it ‘works’)
  7. Support for 40G Ethernet Cards (an enterprise nice to have)
  8. Supports installations in UEFI Secure Boot mode on compatible hardware (important on our increasingly secure desktop systems)

Final Thoughts
All in all, a great upgrade (and it should be, it’s been more than three years since the last major release – thanks Red Hat). These features (and others we will talk about later) bring CentOS 7 into the modern age. We will talk about the bigger features and some of the more interesting smaller ones at a later time, but hit us up below for your experience!

Terrence T. Cox

A veteran of twenty years in Information Technology in a variety of roles. He has worked in development, security and infrastructure well before they merged into what we now call DevOps. He provides training in Linux, VMWare, DevOps (Ansible, Jenkins, etc) as well as containers and AWS topics.

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