Patent ID: 8352665

Claim:
A computer system comprising: a server having an IO bridge; a switch that has a first IO bridge for connecting with the IO bridge of the server through a bus, and a plurality of second IO bridges corresponding to slot positions of the switch, said second IO bridges being connected to IO devices through a bus; a bus number assignment management table for fixedly assigning mutually different PCI bus numbers to the plurality of second IO bridges that correspond to the slot positions of the switch, the bus number assignment management table registering information to fixedly assign the PCI bus number to the second IO bridges, wherein a virtual switch is formed in the switch by referring to the bus number assignment management table; and a switch VS bridge table for controlling a virtual bridge set in the virtual switch; wherein the virtual switch connects the server and the IO devices together by a virtual bridge set up based on the first IO bridge and the second IO bridge that are connected together through a bus, wherein the server is a physical server, and the physical server has one or a plurality of logical partitions, and a hypervisor for setting up and controlling the logical partitions, wherein the computer system comprises a plurality of physical servers, wherein when the logical partition of a certain physical server is dynamically reallocated to another physical server, the bus number assignment management table is not updated, but the switch VS bridge table is updated, and wherein the logical partition that was migrated to the other physical server takes over the PCI bus number used before migration to use the IO device.