1. A method for concurrent removal of processor capacity from a running computer having a resource controller being configured to control a physical resource pool including the actual physical resources, and a capacity virtualizer being configured to provide multiple sets of virtual resources from a capacity virtualizer resource pool, whereby said provided sets of virtual resources allow hosting of independent operating systems concurrently, the method comprising the steps of: said resource controller requesting said capacity virtualizer to reduce said capacity virtualizer resource pool, said capacity virtualizer removing resources from said capacity virtualizer resource pool, and said resource controller disabling physical resources corresponding to the resources removed from said capacity virtualizer resource pool.