- Red Hat Linux Server - Whrelf Siemens
Red Hat Enterprise Linux (RHEL) is a commercial Linux OS that is designed for businesses that need full support and the highest amount of reliability possible for mission critical applications. Historially, RHEL has been a derivative of the Fedora Linux project with features and release cycles that meet the requirements of Red Hat's commercial customers.
RHEL 5 was based on Fedora Core 6. RHEL 6 Beta 1 uses Linux 2.6.32. It's not considered a direct descendant of any Fedora version although it's closest to Fedora 12. Those who want close derivatives of Red Hat Enterprise Linux 6 itself should look into CentOS, Scientific Linux, or Oracle Enterprise Linux. All of them are currently free to download and use.
It has been over three years since Red Hat released RHEL 5 back on March 14, 2007 even though the company has stated that it planned to release major versions every 18 to 24 months. Many system admins and developers have waited a long time for Red hat Enterprise Linux 6. On April 21, 2010, Red Hat took an important step forward by releasing the beta for RHEL 6. It adds many important features that are long overdue. Red Hat has also made the decision to drop Xen with the release of RHEL 6.
Xen Virtualization Support Dropped in RHEL 6 for KVM
KVM (Kernel-based Virtual Machine) replaced Xen as the virtualization product of choice. KVM is a bare metal hypervisor that runs directly on x86 hardware instead of on top of an operating system. It was distributed in RHEL 5.4 in a package called Red Hat Enterprise Virtualization Hypervisor (RHEV-H). With a memory footprint of only 128MB, it can easily be started from flash or a network drive.
From the beta so far, it seems a little slower than a Xen hypervisor despite promises of faster speeds by moving to KVM. The performance may improve later on, but the direction Red Hat is taking on virtualization is clear. No more Xen. Those who do not like this development may want to consider using VMWare instead, which gives OS independence, or use another Linux.
Improvements in RHEL 6
Some of the other improvements Red Hat made with this release include:
- Better power management to reduce power usage.
- Improved scalability with support up to 64,000 CPU cores and 12 TB of memory.
- Comprehensive IPv6 support with support for NFS version 4, CIFS, mobile support (RFC 3775), and ISATAP.
- New ext4 for larger file sizes, reduced filesystem repair times, and better performance. Support for xfs added as well.
- Improved SELinux with new features such as application sandboxing and isolating virtual machines.
The big improvement with version 6 is improved scalability. The Red Hat servers of the future will likely house more CPU cores and more memory while minimizing power and physical space. RHEL 6 gives customers the ability to leverage future technological gains in computer server hardware. The ridiculous memory and CPU maximums today may not seem so ridiculous in a few years.
Free Download of RHEL 6 Beta
As of June 2010, Red Hat Enterprise Linux 6 Beta ISO is available via free download for i386, AMD64/Intel64, System z, and IBM Power (64-bit) platforms at Red Hat's beta website. Download the ISO and burn to a DVD or place the downloaded image on a PXE server. The installation process is similar to RHEL 5 although there are some major changes including those related to storage configuration. The OS needs to be freshly installed. There is no migration process from RHEL 5 with the beta, although it is expected that Red Hat will release a migration guide for those who want to migrate from RHEL 5 to RHEL 6.
Although this is a very important upgrade, especially for those with big hardware needs in the future, the biggest stumbling block to RHEL 6 is the loss of Xen for those who use it extensively. The decision for customers comes down to using KVM, VMWare, or Xen via another Linux distribution.
