Computer system and method for monitoring an access path

A computer system comprising:

• a plurality of servers each comprising a processor, a memory, and an interface;
• a PCI switch coupled to the plurality of servers via the interfaces;
• an I/O device coupled to the PCI switch;
• and
• a management block for managing a configuration of the PCI switch, wherein:
• the management block comprises:
• a switch management block for setting a first access path coupling an active server of the plurality of servers and the I/O device with each other;
• and
• a host management block for instructing a standby server, which takes over the active server, of the plurality of servers to make access to the I/O device used by the active server;
• the switch management block is configured to:
• set, to the PCI switch, the first access path comprising a first virtual bridge coupling the interface of the active server and a first virtual switch with each other, and a second virtual bridge coupling the I/O device, used by the active server, and the first virtual switch with each other;
• and
• set, to the PCI switch, a second access path comprising a third virtual bridge coupling the interface of the standby server and a second virtual switch with each other, and a fourth virtual bridge coupling the I/O device, used by the active server which the standby server takes over, and the second virtual switch with each other, and disable mapping between the I/O device, used by the active server which the standby server takes over, and the fourth virtual bridge of the second access path
• wherein the host management block instructs, after the second access path is set, the standby server to make access to the fourth virtual bridge coupled to the I/O device, used by the active server which the standby server takes over,
• the standby server makes access to the fourth virtual bridge coupled to the I/O device, used by the active server which the standby server takes over, according to the instruction from the host management block, and
• the host management block receives access results from the standby server, and determines, when the access results indicates a failure, that the standby server cannot take over the active server.