A storage device (10,20) comprising: at least one of an active storage unit and a standby storage unit (13a,13b,14a,14b,23a,23b,24a,24b); a communication port (11a,11b,12a,12b,21a,21b,22a,22b) that has a same identifier as an identifier of a communication port of another storage device, and communicates with a host server; a communication processing unit (104,204) that transmits first information on the storage device in response to polling from a monitoring server and receives second information from the monitoring server, which is set on the basis of both of the transmitted first information and information transmitted from another storage device in response to the polling from the monitoring server; and a failover processing unit (103,203) that inactivates the communication port of the storage device having been activated when the failover processing unit determines, based on the received second information, that abnormality has occurred in a communication path between the other storage device and the storage device, and determines, based on the polling from the monitoring server, that abnormality has occurred in a communication path between the storage device and the monitoring server, and that activates the communication port of the storage device having been inactivated when the failover processing unit determines, based on the received second information, that abnormality has occurred in the communication path between the other storage device and the storage device, and determines, based on the polling from the monitoring server, that abnormality has occurred in a communication path between the other storage device and the monitoring server. at least one of an active storage unit and a standby storage unit (13a,13b,14a,14b,23a,23b,24a,24b); a communication port (11a,11b,12a,12b,21a,21b,22a,22b) that has a same identifier as an identifier of a communication port of another storage device, and communicates with a host server; a communication processing unit (104,204) that transmits first information on the storage device in response to polling from a monitoring server and receives second information from the monitoring server, which is set on the basis of both of the transmitted first information and information transmitted from another storage device in response to the polling from the monitoring server; and a failover processing unit (103,203) that inactivates the communication port of the storage device having been activated when the failover processing unit determines, based on the received second information, that abnormality has occurred in a communication path between the other storage device and the storage device, and determines, based on the polling from the monitoring server, that abnormality has occurred in a communication path between the storage device and the monitoring server, and that activates the communication port of the storage device having been inactivated when the failover processing unit determines, based on the received second information, that abnormality has occurred in the communication path between the other storage device and the storage device, and determines, based on the polling from the monitoring server, that abnormality has occurred in a communication path between the other storage device and the monitoring server.