Updated xen packages that fix various bugs are now available for Red Hat Enterprise Linux 5 Extended Update Support.

Xen is a high-performance and secure open source virtualization framework. Virtualization allows users to run guest operating systems in virtual machines on top of a host operating system.

This update fixes the following bugs:

* With a large number of virtual block devices (VBDs) or virtual guests, looking for duplicate devices could take a very long time and significantly increase overall boot time. With this update, this procedure has been optimized not to require XenStore, so that virtual guests now boot much faster. Additionally, this update also ensures that the domain record counter contains a correct value when a XenStore transaction is canceled. Note that when you add a network interface controller (NIC) with an automatically generated MAC address, this address is not verified. Avoid using a combination of hard-coded and automatically assigned MAC addresses, as this can lead to a guest network failure. (BZ#666802)

* Previously, creating a new domain caused a hot plug script to perform an additional check of disk sharing capabilities. With a large number of virtual block devices (VBDs), this operation could take a long time, and an attempt to create a new domain could fail due to a timeout. Since a similar checking mechanism is already implemented in the xend service, this update removes this algorithm from the hot plug script, so that it no longer causes a domain creation to fail. (BZ#680928)

Users of xen are advised to upgrade to these updated packages, which resolve these issues. Note that after installation, the xend service must be restarted for this update to take effect.