Red Hat is to provide a taster of the upcoming version of Red Hat Enterprise Linux (RHEL) by adding Xen into the current version of RHEL.

Version 4 becomes 4.5 and is the first version of the OS to include the open source Xen, which uses para-virtualisation technology to enable virtual machines. Xen is already included in the latest version of the Fedora kernel, Red Hat's community release, and is also part of Novell's SuSE Linux Enterprise 10.

The virtualisation in RHEL 4.5 allows that version of the OS to be a para-virtualised guest in RHEL 5, which then allows those who want to move quickly to RHEL 5 to run existing setups on top of the new OS.

The next full release of RHEL, version 5, is at the beta stage, will include full virtualisation capabilities, and is due out before the end of this month. Red Hat said that adding Xen into the earlier version was part of its policy of keeping existing versions alive despite the imminence of an update.

RH product development manager Scott Crenshaw said in November that open source virtualisation is the driving force behind the release of RHEL 5.