BUSY TIMEOUT EVASION SYSTEM HAVING LEVELED BUSY RATE

摘要

PURPOSE:To give a fast information processing system more priority states than a slow system with regard to a magnetic disk device which is shared between plural information processing systems with different processing speeds, to level the busy rate, and to evade timeout. CONSTITUTION:When the system with a fast processing speed is a channel 1 and the slow system is a chennel 2, the systems 1 and 2 use the magnetic disk device 6 selectively through magnetic disk controllers 3 and 4 and an adapter 5. The circuit of the adapter 5 regards the side of the controller 3 as its own system and the side of the controller 4 as the other system during control and the channel 2 selects the device 6 in a neutral state; and a busy signal is returned even when the side of the channel 1 is selected when the disk device is in use, but when the use is finished, a device end is sent out to both channel sides. Then, the priority circuit of the side of the channel 1 operates to disallow the use of the device 6 in the neutral state from the side of the channel 2 because the device appears to be busy. The side of the channel 1 selects and finishes by using the device, and then when reuse said side is reused finished, priority is moved to the side of the channel 2.