Red Hat Enterprise Linux 7 was released at the beginning of last month, and, as expected, its free derivative CentOS 7 has arrived. This is the first release since CentOS officially joined with Red Hat, so eyes are peeled to see how things have changed. The first change is a welcome one — CentOS 7 arrived almost exactly one month after RHEL 7. Previous major version updates have taken significantly longer, with the bump from version 5 to 6 taking eight months. Point releases are usually quicker, but this is the first time we’e seen CentOS track its parent distro’s release schedule so closely.
As you might expect with a major version bump, there are a number of significant changes in CentOS 7, so without further ado, here are the highlights.
Traditionally, upgrading major point releases has required a reinstall. CentOS 7 is the first release that includes a supported upgrade path from the latest version 6 release to version 7. Note that in-place upgrades won’t work if you’re using an older version of CentOS. At the time of release, tools needed for in-place upgrades were still being tested, but we can expect to see them released soon.
Support For Linux Containers
Containers have seen huge adoption recently, as a lightweight and efficient alternative to virtualization. CentOS 7 includes enhanced support for containers including Docker, a company that has a close relationship with Red Hat.
Containers allow for the running of multiple isolated Linux systems on a single host, but unlike virtualized instances, there’s no need to run multiple operating systems for each container — they all use the same kernel and only include the components needed to run applications.
CentOS will also be releasing Docker images as part of an extended range of content offerings, which will include various cloud images.
XFS As The Default Filesystem
The change to XFS as the default CentOS filesystem introduces a number of advantages, including the ability to scale filesystems to 500 TB, and performance benefits, particularly for parallel I/O operations.
Switch To Systemd
After a long wait and what seemed like interminable debate, the venerable init system has been retired and replaced by Systemd, which incorporates features that help enhance scalability and optimize performance.
As of writing, only the x86_64 version of CentOS 7 is available, but over the coming months we can expect to see 32bit x86, ARM and PowerPC compatible releases.
One of the most interesting changes that the bringing of CentOS under the Red Hat umbrella promised is Special Interest Group releases — versions of CentOS tailored to specific applications like web hosting. It appears that SIGs are still in a community-building phase and we won’t be seeing releases for some time yet.
These are just a few of the new features in CentOS7. If you’re interested in seeing the full list, take a look at the release notes.