1. A method for controlling system switching in a hot standby system in which an active computer and a standby computer share a storage, the method comprising the steps of: recording in a storage area, when a write I/O request for the storage is made, information about the I/O request currently processed; verifying information recorded in the storage area by use of the standby computer when a failure occurs in the active computer; and recovering the storage when write is currently processed as a result of verifying the information.