Is RHEL 7 better than RHEL 6

Viewed: Red Hat Enterprise Linux 7 RC

Three and a half years after the introduction of Red Hat Enterprise Linux (RHEL) 6, Red Hat recently released the successor's release candidate to the general public. The new generation of distribution geared towards corporate customers is much more modern and brings numerous changes; including container virtualization, a new standard file system and an otherwise rarely used standard desktop.

Container virtualization

RHEL7 will bring Docker, a management tool for container virtualization that is currently on everyone's lips. Docker can bundle applications together with the system components and libraries they need into packages that run in a sealed-off area using the namespace techniques of current Linux kernels. With these "Linux containers", the software and its system environment run directly under the host kernel, but cannot see anything else that is going on on the host.

This approach avoids the overhead that the virtualization of complete systems via KVM or Xen entails. Docker also contains numerous functions to facilitate the distribution and management of application containers. The container software works closely with Systemd in RHEL7; RHEL7 will also use SELinux to make escape attempts from containers more difficult.

release date

As usual, Red Hat only says things like the often heard in the open source world "It's released when it's ready" when RHEL7 is released. So we have to wait and see until the distribution is "ready for release". If Red Hat stays at the usual pace of development, that should probably be the case in the second half of summer or early autumn.

File system issue

By default, the installer sets up XFS file systems - not only for the root partition, but also for user data and / boot /. XFS has also been drilled out so that it can cope with data storage media of up to 500 Tbytes and delivers decent performance at the same time; so far the limit was 100 Tbytes.

Ext4 is now equipped for data carriers up to 50 Tbytes; The file system currently used by all mainstream distributions as standard supports a maximum of 16 Tbytes in RHEL6. Btrfs remains a technology preview in RHEL7, so the use of the file system is still not covered by Red Hat support; It is quite possible that this will change in the next few years with one of the updates for RHEL7.

Classic desktop

Gnome 3.8 is the standard desktop in "Classic" mode. With the application and locations menu at the top left and the taskbar at the bottom, it looks like Gnome 2 at first glance; Users therefore need less retraining. This desktop interface is provided by some small Gnome 3 extensions that hide the familiar Gnome 3 shell interface. But that this is underneath becomes apparent very quickly; if you accidentally move the mouse pointer all the way to the top left corner when accessing the application menu, the activities view of the Gnome Shell pops up, for example. There are no differences between the system settings and the normal Gnome; the setting options are therefore rare and clear - some love it that way, others lack flexibility.

KDE 4.10 is also included in the distribution, which is largely based on Fedora 19. Red Hat has only taken over the most important components from Fedora. Instead of the around 13,500 Fedora 19 source packages, RHEL7 is based on only around 2500 source RPMs. Therefore, RHEL7 lacks some well-known applications, including desktops like Cinnamon or Mate. This and other software will probably be available again from the EPEL (Extra Packages for Enterprise Linux) operated by the Fedora project.

Further innovations

RHEL has also received a more modern installer via the Fedora basis, which is largely identical to the much-criticized installation program of current Fedora versions. Due to the significantly younger substructure compared to RHEL6, many components of RHEL7 are much more modern than RHEL6 - the kernel, for example, is no longer based on Linux 2.6.32, but now on 3.10. As usual, Red Hat has already built in some functions that were only included in later kernel versions. The RHEL7 kernel also contains the live patching technique Kpatch, with which security gaps in the kernel can be fixed without restarting; like Btrfs, Kpatch is still a technology preview for the time being. Support for Secure Boot is also new.

KVM remains the virtualization solution of choice; it can now be used to migrate virtual machines in operation from RHEL6 to RHEL7 hosts. For applications that require MySQL, Red Hat sets up version 5.5 of the MySQL subsidiary MariaDB by default. An Apache Httpd version 2.4 is included as a web server. Instead of Upstart, the system and background services are started by Systemd, which also acts as the central instance for resource management with control groups.

New versions of Samba, LDAP and SSHD should improve the central administration of user accounts, systems and services - not only of Linux systems, but also in heterogeneous environments with a Windows Active Directory, because RHEL7 should interact with it much better.

Download & more information

A Red Hat website on the RHEL7 release candidate provides background information on these changes. You can also download it there if you are a Red Hat customer or if you register. But this is not necessary at all because ISO images of the distribution can be accessed free of charge via numerous web servers - in Germany, for example, via those of the Esslingen University of Applied Sciences or Chemnitz University of Technology. These images can also be transferred to USB sticks and other data carriers via dd in order to turn them into RHEL installation media. The finished RHEL7 will not be that easy; However, the CentOS project is already planning a fully compatible clone, which is available free of charge and, like the template, is to be maintained for ten years.

The presentation slides and videos of the Red Hat Summit 2014, which took place in San Francisco in mid-April, provide a lot of additional information about the RHEL7 innovations. Three presentations at the annual Red Hat in-house exhibition were all about container virtualization with RHEL:

  • Portable, lightweight, & interoperable Docker containers across Red Hat solutions (PDF)
  • Linux containers in Red Hat Enterprise Linux 7 beta (PDF)
  • Application-centric packaging with Docker & Linux containers (PDF, video)

The two-hour lecture "Red Hat Enterprise Linux roadmap" provides a broad overview of the innovations in RHEL7. The very informative presentation slides are available free of charge; There is also a two-part video recording on YouTube, which gradually explains the innovations in the various functional areas of RHEL.

(thl)