Red Hat Enterprise Linux 5.4 beta with KVM
Red Hat has released a beta version of Red Hat Enterprise Linux (RHEL) 5.4. The new version's most prominent new feature is KVM (Kernel-based Virtual Machine), a virtualisation technology which was integrated into the main development branch of Linux quite some time ago.
In the beta of RHEL 5.4, KVM supports various versions of RHEL as well as Microsoft Windows XP, Windows Server 2003 and Windows Server 2008 as guest systems. Paravirtualised drivers are provided to enhance I/O performance. However, KVM requires processors with virtualisation functionality (as offered by the majority of the current AMD and Intel processors); it does not provide complete paravirtualisations of modified guest systems like Xen.
All of Red Hat's announcements regarding the beta emphasise that Xen virtualisation will also continue to be supported in future versions of the RHEL5 series. Considering Red Hat's takeover of KVM developers Qumranet last September and the Xen developers' continuing struggle to get their technology integrated into the main development branch of Linux, it does seem that Red Hat intends to rely on KVM in the long run; migration tools are being developed to facilitate switching from Xen to KVM in the future.
Another new feature is the support of Intel's VT-d (Virtualisation Technology for Directed I/O) and SRIOV (Single Root I/O for Virtualization) in KVM and Xen. RHEL 5.4 will also offer FUSE (File System in Userspace) and drivers and tools for FCoE (Fibre Channel over Ethernet) and Clustered Samba have been integrated as technical previews. While Red Hat has improved the support of the Ext4 file system first introduced with RHEL 5.3, the file system still retains its technical preview status.
As is customary with "point releases" of RHEL, the new version also contains numerous updates, bug fixes and minor enhancements. For instance, the developers incorporated the cnic driver for Broadcom LAN chips – which was recently integrated for 2.6.31 – into their 2.6.18-based kernel and they also updated numerous audio, graphics and network drivers. Find details in the beta announcement and in the more comprehensive release notes.