Patent ID: 8683109

Claim:
A computer system, comprising: a plurality of physical servers each having an IO bridge and one or more logical partitions; 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; and a bus number assignment management table for fixedly assigning mutually different PCI bus numbers to all of the plurality of second IO bridges; wherein the bus number assignment management table is for registering information to fixedly assign the PCI bus numbers to the second IO bridges, and said second IO bridges are connected to IO devices through a bus; wherein a virtual switch is formed in the switch by referring to the bus number assignment management table; 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 bridges that are connected together through a bus; wherein the computer system further comprises a switch VS bridge table for controlling the virtual bridge set in the virtual switch; wherein when the logical partition of a certain physical server is dynamically migrated 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.