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.