Abstract: A method of controlling data which is stored into a common storage in a multiprocessor system having a common storage which can be accessed from a plurality of computers is disclosed. Particularly, a method of controlling shared data using an extended storage as a common storage is disclosed. The copy of the data of a part of or all of a shared data set in an input/output device and the copy data control information to control the copied data are stored into the common extended storage. In the case of accessing the data in the common extended storage, the mutual exclusion among a plurality of computers and the consistency control of the data are realized by referring to the control information stored in the common extended storage.

Abstract: In an information processing system including a file shared by computer systems each having a central processing system and a main memory, a method for controlling access to the shared file includes a step of storing blocks read from the file into the main memory when the blocks of the file are updated, and a step of comparing at least a portion of the blocks held in a cache memory with at least a portion of the blocks stored in the main memory. When the comparison of at least the portion of the blocks held in the cache memory with at least the portion of the blocks stored in the main memory indicates mismatching, the block is read from the file into the main memory, and when the comparison indicates matching, the block of the main memory is updated. The data to be updated may be in a resident area, an input/output buffer or a same area.