The very nature of the GNU Public License (GPL) ensures that any project, company or organization which builds products based on GPL licensed software has to release the source for that derivative work. And although it is possible to do this in an obscure way which isn’t very helpful, that isn’t what Red Hat does. Red Hat has been a pillar of the open source community for more than twenty years. Its own distributions, and the distributions to which it contributes, play a major role in the Linux eco-system. One of those distributions is Red Hat Enterprise Linux (RHEL). It is a commercial distribution aimed primarily at large businesses. As a commercial product, there is no free version. If you want to run RHEL, you need to buy a license.
However, because RHEL is based on open source software, Red Hat also publishes the source code that it used to build it. The name Red Hat is trademarked, so it isn’t possible to just rebuild the sources and publish the distribution. But it is possible to create a new distribution based on those sources that offers binary compatibility and has the same feaure set as RHEL. There are several projects that do this RHEL re-build, including Scientific Linux and Oracle Linux, but probably the most well known of these RHEL based distributions is CentOS.
There is one other little bit of information that completes our picture about CentOS. In January 2014, Red Hat basically took over the CentOS project. The CentOS trademark was transferred to Red Hat, and the company starting paying most of the CentOS lead developers. This means that CentOS is now an official RHEL clone!
In June 2014, Red Hat released the next major version of its enterprise distribution – Red Hat Enterprise Linux 7. CentOS subsequently published CentOS 7.0, the first version since CentOS was sponsored by Red Hat.
What’s new about CentOS 7?
CentOS 7 introduces several major changes over the CentOS 6.x line. First, CentOS now uses XFS as its default file system. Second, OpenJDK-7 is now the default JDK. Third, “initd” has been replaced by “systemd”. Other changes include the use of the Linux Kernel 3.10.0, support for Linux Containers, and the inclusion of the Open VMware Tools and 3D graphics drivers out of the box.
There is also a new numbering scheme with CentOS 7. The official name of the first release is CentOS 7.0-1406. The “7.0” comes from RHEL 7.0 and the “1406” indicates the month stamp of the code included in the release (e.g. June 2014 ). The month stamp will allow CentOS to make re-spins with the latest security and bug fixes while still retaining the connection to the RHEL release number.
Download the .iso DVD from the CentOS website and burn it onto a disc. Note that CentOS 7 only supports 64-bit processors. Boot your PC from the DVD. You may need to change your BIOS settings to get your PC to boot from an optical drive. At the boot menu, select “Install CentOS 7” and press ENTER.
Pick your installation language and click “Next”. On the installation summary page check for any items which need attention (those marked with an exclamation mark). One item which will certainly need attention is the “Installation Destination.” Click the icon and select the devices that you would like to install to. CentOS offers an automatic partitioning option, as well as the ability to do your own partitioning.
As mentioned above, CentOS now uses XFS as its default file system. If you want to use another file system you will need to use the “I will configure partitioning” option. According to Red Hat, XFS is faster than EXT4 in real world uses. XFS was originally designed at Silicon Graphics, Inc. and can support file systems up to 16 exabytes (about 16 million terabytes). XFS also supports single files up to 8 exabytes (around 8 million terabytes) and directory structures with tens of millions of entries. XFS also supports metadata journaling which makes crash recovery quicker.
The default software selection is just for a minimal system, without a GUI. Click “Software Selection” to choose between a “File and Print Server,” a “Basic Web Server,” a “Virtualization Host,” or a GNOME or KDE desktop. CentOS 7 has moved to GNOME 3, much like the Fedora project.
When you are ready, click “Begin Installation.” During the installation process you can set the root password and add at least one user account.
Once the installation has ended click “Reboot” to restart your system.
The system will either reboot to the command line or to the desktop depending on which packages you installed. The “GNOME Desktop” install along with the “Internet Applications” and “Office Suite and Productivity” add-ons makes a reasonable desktop. Of course, many people will use CentOS as a server, however the desktop options show that it can be tweaked for almost any configuration from server or virtualization host to a “Development and Creative Workstation.”
CentOS has a strong user community; if you have any problems with the installation or any questions about using CentOS then try the forums.