The changes in Red Hat Enterprise Linux 5.7
by Thorsten Leemhuis
The main improvements to the latest release of RHEL series 5 are optimised virtualisation with KVM and Xen, as well as new and revised drivers. Slowly but surely, the series is nearing the end of the first and most active phase its lifecycle.
Red Hat has published Red Hat Enterprise Linux 5.7, the seventh major revision of RHEL 5, which was launched in March 2007. As with RHEL 6, which was introduced last autumn, series 5 is currently in the first of four lifecycle phases; the new version not only includes the bug fixes produced over the past few months, but also refreshed drivers, optimisations, and new features.
A few improvements to the KVM hypervisor in RHEL 5.7 are designed to improve the emulation of CD drives and solve problems related to the boot sequence. In addition, Red Hat has reduced the time needed for live migration, i.e. the shifting of guest systems between hosts on running machines.
On 5.7, 32-bit guest systems virtualised with Xen are reportedly faster, and Xen guests are also said to boot faster. Furthermore, they can address not just 100, but up to 256 storage drives. PyGrub now offers support for kernels compressed with XZ, which the Linux kernel has supported since version 2.6.38.
RHEL 5.7 includes dozens of updated drivers and a few more recent ones so the Linux distribution based on Linux kernel 2.6.18 can also run on a lot of modern systems. The changes include storage drivers for fibre-channel adapters and SAS-Chips; version 08.101.00.00 of SCSI driver mpt2sas is also included to add support for devices from WarpDrive series SSS-6200.
The Radeon graphics driver now supports output via DisplayPort on the RV635 (Radeon HD 36xx) and RV730 (Radeon HD 46xx) chips. New and revised network drivers promise better support for 10-gigabit ethernet. For the first time, the distribution includes the iw_cxgb4 driver, which handles T4 series Chelsio RDMA hardware; the atl1e network driver for gigabit chips from Atheros is also part of the package. The qlcnic driver now supports Large Receive Offload (LRO) and Generic Receive Offload (GRO).
In addition, Red Hat says it has improved support for the new processors and chipsets that AMD, Intel and IBM have presented over the past few months and are planning to launch soon. Red Hat says it has added new functions for network bridges and improved support for LDAP in Autofs.
Keeping an overview
Series 5 now also includes Red Hat's Subscription Manager and Subscription Service, which was added to RHEL 6 in version 6.1. The Subscription Manager allows Red Hat customers to more easily see which services (purchased as part of a Red Hat subscription) are being used on a system; it can also be used to install updates, an option designed to increase availability and reduce installation time.
OpenSCAP provides support for the Security Content Automation Protocol (SCAP). It includes a developer library and tools that detect whether all security updates have been installed, all critical security settings are properly configured, and whether your system may have been compromised. In addition, a wide range of improvements were made to the System Security Services Daemon (SSSD).
Customers with the High Availability/Cluster Add-On now have full support when using the XFS file system.
RHEL 5.8 will probably be released in around six months time, as Red Hat is now trying harder to produce a new minor release at that frequency. Series 5 will, however, reach the end of its first lifecycle phase in the fourth quarter of this year. It will then enter the second production phase, which will last a year; from that point onwards there will be no more major new functions, and support for new hardware will only be added if it does not require a lot of work. Anyone who wants to use new hardware with RHEL, will eventually have to switch to a more recent RHEL generation.