1. A failover method for use with a computer system in which the operating systems are booted by an external disk device, wherein plural servers are connected via a network to the external disk device, each of the servers incorporates therein a logic partition module for configuring at least one logic partition in each server, and a task being executed by a working server in the computer system is taken over by a standby server in the computer system when a failure occurs in the working server, the method comprising a step of detecting the failure that has occurred in the working server; a step of specifying the location of the failure; a step of specifying the logic partition that is affected by the failure, depending on the specified failure location; a step of shutting down the logic partition; a step of searching for a standby server for taking over the task from the working server in which the failure occurred; a step of configuring in the standby server a logic partition equivalent to the logic partition affected by the failure; a step of establishing the correspondence relationship between the logic partition configured in the standby server and the external disk device for booting the operating systems in logic partitions; and a step of starting the configured logic partition, wherein the step of specifying the logic partition that is affected by the failure detects whether or not the failure affects the logic partition module; and if the logic partition module is affected by the failure, all the logic partitions in the working server are regarded as affected by the failure.