Patent
1994-06-16
1997-12-02
Lee, Thomas C.
395427, G06F 732, G06F 1210
Patent
active
056946198
ABSTRACT:
Disclosed is an exclusive control method in an I/O subsystem having an exclusive controller which is provided with an exclusive control table and which permits a host interface to use the I/O device when the I/O device is not used by any other host interface while prohibiting the use when another host interface is using the I/O device. The method comprises the steps of: allotting a logical path number to each of the host interfaces of each of the input/output interface portions; Judging whether or not the I/O device is being used by another host interface by reference to the exclusive control table when a request for use of the I/O device is input from a host interface to which a predetermined logical path number is allotted; permitting the host interface which has required for access to use the I/O device when the I/O device is not in use, while setting a flag indicating that the I/O device is "Occupied" in the exclusive control table in correspondence with the allotted logical path number; and changing the flag to a flag indicating that the I/O device is "Vacant" when the use of the I/O device is finished.
REFERENCES:
patent: 4604709 (1986-08-01), Blout et al.
patent: 5031091 (1991-07-01), Wakatsuki et al.
patent: 5167034 (1992-11-01), MacLean, Jr. et al.
patent: 5247638 (1993-09-01), O'Brien et al.
Fujitsu Limited
Krick Rehana Perveen
Lee Thomas C.
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