Fault tolerance and fault tolerance control method

摘要

Provided is a fault-tolerant system with a plurality of computers which form a majority voting redundancy configuration, each of which is provided with: a task communication unit (140) for acquiring process content from a program which operates in that computer (110B, 110C); and a message processing unit (142) which receives, from any of the other computers (110A) which form the majority voting redundancy configuration, a prescribed message which indicates the process content of a program which operates on the other computer (110A) and returns a replication permissibility message to the other computer (110A) according to the result of a match determination between the process content indicated by the prescribed message and the process content obtained by the task communication unit (140). The message processing unit (142) of the computer which is the other computer (110A) further executes a process for changing the number of computers (110B, 110C), aside from the other computer, for which the other computer is to await receipt of replication permissibility messages, depending on the process content obtained by the task communication unit (140) of the other computer (110A).