JBoss clustering and Penguin’s Clusterware (bproc) have one thing in common: the view of the the system spans more than a single underlying system. Other systems have this concept as well, but these two are the ones I know best. Virtualization is currently changing how people do work in the datacenter. Many people have “Go virtual first” strategies: all software deployed can only be deployed inside virtual machines. While this simplifies some aspects of system administration, it complicates others: Now the system administrators need tools to manage large arrays of systems.

If you combine current virtualization practices with current cluster practices, you have an interesting sytem. Make a clustered OS instance of Virtual machines and deploy it across an array of embedded Hypervisors. Any one of the VMs that make up the clustered OS image can migrate to a different machine: after running for a length of time, no VM may be on any of the machines that were originally used to run the clustered OS Image.
Such a system would have many benefits. The virtualization technology helps minimize points of failure such that, in theory the whole system could be checkpointed and restarted from a n earlier state, assume that the networking fabric plays nice. System administration would be simplified as a unified process tree allows for killing remote processes without having to log in to each and every node to kill them. Naming service management is centralized, as is all policy for the cluster. Additionally, multiple OS images could be installed on the same physical cluster, allowing clear delineation of authority, while promoting resource sharing. Meta system administrators would see to the allocation of nodes to a clustered image, while department system admins would manage their particular cluster, without handling hardware.