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21 February 2012, 19:08

Red Hat logo What's new in Red Hat Enterprise Linux 5.8

Thorsten Leemhuis

As well as bug fixes and improved hardware support, the eighth minor revision of Linux distribution RHEL 5, which was first released in 2007, also includes new virtualisation and power management features.

A little under five years since it was first released, Red Hat has provided customers with the eighth "minor release" of Red Hat Enterprise Linux (RHEL) 5. Scalability improvements mean that rather than 128 cores, guests virtualised with KVM can now use up to 256 processor cores. Red Hat says it has improved support for clock and timer hardware in KVM guest systems. KVM guests will now boot more quickly and, thanks to updates to the real time clock (RTC) code, RHEL 6 guests running on RHEL 5 hosts will run faster. The Spice client now supports Red Hat Enterprise Virtualization (RHEV) 3.0 and RHEL 6.2 hosts, enabling the remote desktop protocol to be used on wide area networks.

RHEL 5.8 is also able to pass control of CD-ROM drives to paravirtualised Xen guests. For Xen, Red Hat has also improved guest performance, logging and functions for resizing filesystems on virtual disks.

The kernel

The kernel in RHEL 5 is still based on Linux 2.6.18, but with the addition in version 5.8 of support for PCI Express (PCIe) 3.0. The new version also sees the addition of infrastructure for Power Management Quality of Service (PM QoS), a feature long merged into the main Linux development tree. PM QoS enables drivers and userland software to report CPU and network latency or network throughput requirements, enabling the system to throttle back to the required speed and avoid wasting electricity by always using the fastest operating mode.

As is normal with RHEL minor updates, the developers have also updated many drivers. In particular there are updated drivers for network and storage chips, which offer improved support for recent hardware. There are also new audio, I2C, SATA and USB drivers for yet-to-be-released Intel Platform Controller Hubs (PCHs) – probably the Panther Point chips (part of the Platform which used Ivy Bridge processors) that Intel is expected to unveil around Easter time.


  • RHEL 5.8 now includes iotop, a Top-like tool which shows which processes are reading or writing to storage media.
  • Red Hat has added binutils220, a new, optional binutils which enables the use of some new features offered by AMD's Bulldozer processors.
  • The installation program now supports the configuration of IP over Infiniband (IPoIB) hardware, making it easier to install over Infiniband adapters.
  • OpenSCAP (Open Security Content Automation Protocol) now supports SCAP 1.1 (Security Content Automation Protocol).

The release notes offer a brief overview of these and many other changes in RHEL 5.8. A more detailed list of changes, including links to entries in the tracking database, can be found in the technical notes. In parallel to the release of RHEL 5.8, Red Hat employee Mark J Cox published a blog entry – "Mark J Cox : Enterprise Linux 5.7 to 5.8 risk report". Cox offers a few insights and a short analysis of the security problems that Red Hat has addressed between versions 5.7 and 5.8.

Life cycle

Because RHEL 5 is, until the end of this year, in the first of its three life cycle phases, a further new version, RHEL 5.9, including changes on the same scale as those in version 5.8, should be released later this year. Compared to previous RHEL 5 minor releases, the scope and significance of the changes continues to decline noticeably, with major changes already merged into RHEL 6 or tending to be fast-tracked into minor updates for the latter. With RHEL 5 gradually heading into the second phase of the RHEL life cycle, this trend is set to become more pronounced – once this happens Red Hat will normally not add new features and will only add support for new hardware where it's not too much trouble.

As a result, the distribution's suitability for use in newer systems will gradually decline. RHEL 5 nevertheless still has half of its standard life cycle before it, with Red Hat having recently extended the life cycle of both RHEL 5 and RHEL 6 from seven to ten years. Extended Life Cycle Support (ELS) adds a further three years to this. By then, however, most current installations are likely to be just so much scrap metal.

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