PURPOSE: To rewrite an arbitrary part of information block at high speed by receiving the position, the length and the information of a part to be updated and updating by a disk controller at the time of having an information block updating request from a processor.
CONSTITUTION: At the time of having the information block updating request to the controller 4 from the processor 1, the controller 4 inspects whether there is a relevant block in a disk cache memory 5 or not and informs a result to a channel device 3. When it is not stored in the memory 5, according to a command from the informed channel device 3, the entirety of the relevant block in a disk device 6 is updated. When it is stored, the channel device 3 feeds the position and the information of the position and the length of a part to be updated in the relevant block and partial updating information from a main storage device 2 and the controller 4 partly updates the information in the disk cache memory 5. According to this constitution, the transfer of especially unrequired information can be avoided and the information can be partly rewritten at high speed.
KIJIRO SHIGERU
SHIRAYANAGI YOSHIRO
KURANO AKIRA
