Use of Virtual Machines/hypervisors

Since Virtual Machine technology, like VMware, Xen, Virtual Iron, Microsoft Hyper-V, and IBM z/VM run other (guest) operating systems as application programs, the hosting program, the hypervisor, has incredible power to start/stop/modify its application program (the guest operating system and the applications it runs). Experience has shown how powerful this is in IBM z/VM with a very strong command and tracing capability for recreating and debugging guest problems.

Oh, by the way, you do realize that you should be ready for that major emergency, when you need to use that second-fault tool, right? You should be familiar with the second-fault tools your vendor (and your product) has to offer you, before you set up the parameters on your second fault tool to solve the current urgent "problem du jour".