Xen will soon offer native hosts fail-over

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At the recent Xen Summit 2008 in Tokyo a specially interesting project finally reached version 1.0: Kemari.
The project was presented for the first time in April 2007 but only now it reaches a version stable enough to be marked as GA.

Developed by Yoshiaki Tamura, Kemari is a patch for Xen 3.3 that brings host fail-over.
It works with both Linux and Windows guests OSes.

A briefly description tells enough to understand how it works:

Kemari in VMM taps event channel, pauses the guest (not suspend), prepares for transfer, and Kemari in userland transfers the guest. On failover, Kemari on the secondary restores the guest, and the backend drivers in dom0 set up the backend rings from the state of the shared rings in the guest

Here a video where a Windows XP virtual machines survives the shut down of one node in a hardware cluster of two:

The exiting news is that Kemari is now part of the Xen roadmap, and this means that the open source hypervisor may offer out-of-the-box fault tolerance as soon as it hits version 3.4.
Citrix will be probably very happy. We wonder if Marathon Technologies will be happy as well.