HPC Cluster Blog – RHEL 7 Released

On June 10th of 2014, Red Hat launched version 7 of the Red Hat Enterprise Linux (RHEL) operating system. RHEL 7 was a long time coming and adds a bunch of great features and fixes from previous versions. There are lots of improvements but we will be just going over a few key ones in this article:

File Systems:
The default filesystem is now XFS instead of ext4. The ext4 filesystem has some pretty big limitations when it comes to large filesystems topping out at 16TB. These days with the prevalence of 4TB and bigger drives, 16TB is pretty small, and is certainly a limiting factor. Most large filesystems Advanced Clustering deployed were XFS, but making this the default will help with consistency and make it more likely bugs are found and squashed more quickly. Using XFS used to be an additional cost with RHEL but is now included with the software. RHEL 7 also includes a preview of the Btrfs file system, which is a ground up new filesystem that has been in development for awhile. Btrfs has some interesting features like integrated device management and RAID features, removing the need for technologies like LVM and the linux software RAID stack.

Kernel:
RHEL7 finally has moved in to the 3.X kernel tree, and will include 3.10. Almost all Linux kernel development has been happening in the 3.X tree for a number of years, so this is a long overdue change. 3.X will provide better hardware support and new features.

Compilers:
RHEL 6 included the gcc version 4.4 compiler suite (c, c++, fortran, etc). RHEL 7 has brought that up to 4.8. The new compilers provide lots of new features and better optimization for the latest AMD and Intel processors and instruction sets. In the past Advanced Clustering has been building and shipping a newer version of gcc to include with RHEL 6 deployments since there could be a significant performance boost by using newer compilers on current hardware.

What about CentOS?
The CentOS Linux distribution is a re-compiled completly free version of Red Hat Enteprise Linux. The CentOS team is currently working hard to release the 7.0 version. Currently they have released a QA release, and nightly builds. There is no scheduled release date yet, but the progress is moving quickly and we would expect to see a release soon.

Deploying RHEL 7 on your next cluster
Advanced Clustering is currently evaluating RHEL 7 and testing it with our hardware, and many common software packages. Currently we aren’t recommending installing 7 on a new system just yet. We are working hard to make sure we don’t have major compatibility issues and that when we recommend the 7 release, it will be stable and work for you. Please contact us at [email protected] for more details.