High Availability Virtual Machine Cluster

A high-availability cluster of virtualization systems in which failover is supported at least in part by maintaining for each virtual machine an encapsulated representation of virtual machine state, including at least a description of the hardware system virtualized together with backing state therefor, in storage accessible to each virtualization system of the cluster, and by re-instantiating in response to a virtualization system failure and based on the respective descriptions of hardware systems virtualized, one or more virtual machines and resuming respective computations thereof based on the respective backing states.

A method of operating a cluster of virtualization systems, the method comprising:

• maintaining, for each virtual machine executing on a virtualization system of the cluster, an encapsulated representation of virtual machine state in storage accessible to each virtualization system of the cluster, wherein the virtual machine state includes at least a description of a hardware system virtualized and an image of virtualized memory state for the corresponding virtual machine;
• and
• transitioning at least one of the virtual machines to another virtualization system of the cluster and resuming computations of the transitioned virtual machine based on state encoded by a corresponding one of the virtual machine states represented in the storage.

A computer program product encoded in one or more computer readable media, the product comprising:

• an availability agent executable in association with respective virtualization systems of a cluster, the availability agent including an instruction sequence executable to resume, on the associated virtualization system, execution of a virtual machine that previously executed on another virtualization system of the cluster,
• wherein the availability agent maintains, for each virtual machine for which the associated virtualization system may be called upon to resume computations, an identifier for identifying in shared storage a representation of virtual machine state that includes at least a description of the a hardware system virtualized and an image of virtualized memory state.