Data transfer control system for virtual machine system

DETAILED DESCRIPTION Accordingly, it is a general object of the present invention to provide a novel and useful data transfer control system in which the problem described above is eliminated.
Another and more specific object of the present invention is to provide a data transfer control system for a virtual machine system which includes a plurality of virtual machines, a main storage and an external storage which is accessible by each of the virtual machines, comprising storage means for storing at least transfer priorities of each of virtual machines, queuing means for making a queue of data transfer requests which request data transfers between the main storage and the external storage and are received from operating systems which operate on each of the virtual machines, limiting means coupled to the storage means and the queuing means for limiting a transfer data length of one data transfer which is requested by each data transfer request in the queue of the queuing means depending on the transfer priority of the virtual machine from which the data transfer request is received, so that a data transfer is made in divisions if the requested transfer data length exceeds a length limit determined by the transfer priority, generating means coupled to the limiting means for generating a first data transfer request in place of each operating system with the transfer data length determined by the limiting means so as to start a first data transfer between the main storage and the external storage, and calculating means coupled to the generating means for calculating a data length of a remaining transfer data which remains to be transferred when the first data transfer is completed and for automatically generating a second data transfer request requesting transfer of the remaining transfer data, the second data transfer request being inserted in the queue of the queuing means so that the remaining transfer data is transferred between the main storage and the external storage in one or a plurality of second data transfers