Virtuozity

Link: http://nss.cs.ubc.ca/remus/

Remus is an open source project which provides fault tolerance for virtual machines (VMs) running on the Xen hypervisor. The actual release 0.9 works with tip of the xen-unstable repository, supports paravirtualization and hardware VMs in various 32- and 64-bit configurations for Windows and Linux.

Remus provides transparent, comprehensive high availability to ordinary virtual machines running on the Xen virtual machine monitor. It does this by maintaining a completely up-to-date copy of a running VM on a backup server, which automatically activates if the primary server fails. Key features:

• The backup VM is an exact copy of the primary VM. When failure happens, it continues running on the backup host as if failure had never occurred.
• The backup is completely up-to-date. Even active TCP sessions are maintained without interruption.
• Protection is transparent. Existing guests can be protected without modifying them in any way.

I am looking forward to the day Remus will be announced stable and hopefully integrated into XenServer sooner than later!