1. A virtualization system comprising: a server comprising memory storing first instructions and one or more first processors configured to execute the first instructions to activate a plurality of virtual machines, each of the plurality of virtual machines being assigned identification information and capable of executing a predetermined function; and a virtual machine control device comprising memory storing second instructions and one or more second processors configured to execute the second instructions to: create a function correspondence table in which the assigned identification information is associated with a predetermined function that is executed by at least one of the plurality of virtual machines, wherein the at least one of the plurality of virtual machines specifies the associated predetermined function in the function correspondence table based on the assigned identification information; and generate a number of items of the identification information equal to a number of predetermined functions executed by the plurality of virtual machines multiplied by a redundancy value.