Patent ID: 7254733

Claim:
A method for shutting down virtual machines in a computer system comprising a real computer and a virtual machine operating system, said virtual machine operating system comprising a common base portion and a plurality of virtual machines sharing said common base portion, said method comprising the steps of: receiving a shutdown signal from said real computer, said shutdown signal specifying a time period for shutdown of said common base portion or said virtual machine operating system; determining a time period for shutdown of said virtual machines by subtracting a time required to shutdown said common base portion from the specified time period; sending requests to said virtual machines to shut down in an orderly manner within said time period determined for shutdown of said virtual machines; determining when and if each of said virtual machines shuts down in an orderly manner; and if all of said virtual machines shut down in an orderly manner before said time period determined for shutdown of said virtual machines lapses, before lapse of said time specified in said shutdown signal from said real computer, shutting down said common base portion, and if all of said virtual machines do not shut down in an orderly manner before said time period determined for shutdown of said virtual machines lapses, upon lapse of said time period determined for shutdown of said virtual machines, shutting down said common base portion, said shutting down of said common base portion disrupting any of said virtual machines that did not shut down in an orderly manner.