Patent ID: 8510815

Claim:
A computer system comprising: a plurality of physical computers; an external device which is coupled with the physical computers via a communication device having a plurality of ports; at least one virtual computer operable to be executed on the physical computers; and a determination unit operable to determine whether login to the external device from the virtual computer is acceptable or unacceptable, wherein the virtual computer is allocated an identifier for accessing the external device, wherein, upon receiving a login request to the external device from a certain virtual computer, the determination unit determines the physical computer which is coupled with a port of the communication device receiving the login request based on information of the port of the communication device receiving the login request with reference to a connection information of the physical computer and the communication device, the determination unit compares the identifier allocated to the virtual computer requesting login with the identifier allocated to another virtual computer to be executed on the physical computer different from the physical computer on which the virtual computer requesting login is executed, with reference to allocation information of the physical computer executing the virtual computer and the identifier allocated to the virtual computer, and when the identifier allocated to the virtual computer requesting login agrees with the identifier allocated to the another virtual computer, the login is rejected, when the identifier allocated to the virtual computer requesting login does not agree with the identifier allocated to the another virtual computer, the determination unit searches whether a virtual computer which is defined with the identifier allocated to the virtual computer requesting login is configured, with reference to the allocation information, and the login is accepted when the virtual computer which is defined with the identifier allocated to the virtual computer requesting login, is configured, the login is not accepted when the virtual computer which is defined with the identifier allocated to the virtual computer requesting login, is not configured.