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XenSummit has been a tremendous success this year. Thank you to all the speakers for contributing and to all the attendees for making XenSummit an interactive and fun conference with lots of discussions. You can find presentations on slideshare and videos on vimeo. We will also embedded both in the agenda. The slides are also available for download as zip file.

COLO: COarse-grain LOck-stepping Virtual Machines for Non-stop Service

Virtual machine (VM) replication (replicating the state of a primary VM running on a primary node to a secondary VM running on a secondary node) is a well known technique for providing application-agnostic, non-stop service. Unfortunately, existing VM replication approaches suffer from excessive replication overhead and, for client-server systems, there is really no need for the secondary VM to match its machine state with the primary VM at all times.

In this paper, we propose COLO (COarse-grain LOck-stepping virtual machine solution for non-stop service), a generic and highly efficient non-stop service solution, based on on-demand VM replication. COLO monitors the output responses of the primary and secondary VMs. COLO considers the secondary VM a valid replica of the primary VM, as long as network responses generated by the secondary VM match that of the primary. The primary VM state is propagated to the secondary VM, if and only if outputs from the secondary and primary servers no longer match.

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