Abstract: A method to automatically allocate servers to network services in a data center in real time and without need for operators for a load sharing device is provided. In the method, fluctuations in quantity of requests arriving at the network services can be monitored, the value of the quantity of requests for a subsequent fixed time interval can be predicted and, in accordance with the magnitude of the predicted value of the quantity of requests, the quantity of servers allocated to the network services can be controlled. Here, where traffic of the quantity indicated by the predicted value of the quantity of requests arrives at the network services, the number of servers allocated to the network services can be set in such a way that the average response time to the user terminals is equivalent to a response time threshold value or less set in advance by the operations manager.

Abstract: A system comprises a front-stage center for directly receiving a request from a client through a network, and a back-stage center for receiving the request from the client through the front-stage center. The front-stage and back-stage centers have stand-by servers, respectively. The front-stage center provides a service using a normal server. When detecting that a load on the server increases, a first system control device provides a server for providing the service the load of which increases from the stand-by server commonly provided for a first service and a second service. If the load cannot be supported even by the provision of the server, the first system control device issues an instruction to a second system control device of the back-stage center to support the provision of the service. If the back-stage control device cannot support the load using a normal server, it supports the load using the stand-by server.