A method of operating a virtual machine cluster

Process control system and methods are disclosed. An example method includes operating a first cluster including first virtual machines and first servers and operating a second cluster including second virtual machines and second servers. The example method also includes storing first data from the first virtual machines at a first data store of the first cluster and storing a replica of the first data at a second data store of the second cluster. The example method also includes storing second data from the second virtual machines at the second data store and storing a replica of the second data at the first data store and identifying a failure of the first cluster. The method also includes, in response to the failure, restarting the first virtual machines using the second servers and the replica of the first data at the second data store.