the computer shown in fig2 and includes a cpu a memory an nic and an input output device the management computer 11 may be realized by a program executed on a virtual computer the management computer 11 includes the recovery determination table 303 a data amount obtaining unit 108 the cluster information transfer unit 302 the load information transfer unit 203 and a failure recovery unit 110 the recovery determination table 303 includes the data amount determination table 311 the cluster state determination table 331 and the load information determination table 321 as in the first embodiment of this invention the data amount determination table 311 which is updated more frequently than the other information is stored in each computer because if the data amount determination table 311 stored in the management computer is updated whenever necessary the network traffic may be increased to deteriorate the processing efficiency in the second embodiment of this invention the increase in network traffic is suppressed by the management computer 11 periodically obtaining the information of the data amount determination table 311 stored in the active system computer the data amount obtaining unit 108 obtains information from the data amount determination table 311 stored in the active system computer and stores the information in the data amount determination table 311 of the management computer 11 the cluster information transfer unit 302 receives the cluster information transmitted from the.