Abstract: This invention provides a computer that, on the basis of identifying information for virtual ports for virtual machines in logical partitions, allows per-virtual-machine access control for storage systems. Said computer, which connects to said storage systems, has the following: hardware resources including processors, physical memory, and an I/O adapter; and a first hypervisor that logically divides said hardware resources into one or more logical partitions. Upon receiving an instruction to issue an I/O command to a logical unit of a storage system from a first virtual machine in a first logical partition, the I/O adapter transmits, to said storage system, an I/O command containing first identifying information that identifies a first virtual port for the first virtual machine.

Abstract: A computer has an adapter which is coupled to storage devices; the adapter transmits data and receives data, and measures the transfer amount of data that has been transmitted and received, and the number of I/O accesses, for each virtual computer; a virtualization part, on the basis of the transfer amount of the data, and the number of I/O accesses, acquired from the adapter, computes an upper limit for the data transfer amount and an upper limit for the number of I/O accesses for each virtual computer and reports to the virtual computers; and the virtual computers retain the data to transfer to and to receive from the storage devices in a queue, and the virtual computers control data to output from the queue so as not to exceed the upper limit of the data transfer amount or the number of I/O accesses.