When a primary server executing a task fails in a computer system where a plurality of servers are connected to an external disk device via a network and the servers boot an operation system from the external disk device, task processing is taken over from the primary server to a server that is not executing a task in accordance with the following method. The method for taking over a task includes the steps of detecting that the primary server fails; searching the computer system for a server that has the same hardware configuration as that of the primary server and that is not running a task; enabling the server, searched for as a result of the search, to access the external disk device; and booting the server from the external disk device.