Data search method wherein the court-key-data (CKD) storage subsystem disconnects from the central processing unit when searching

A data searching method for a storage subsystem connected to a central processing unit, said storage subsystem having an external storage unit for storing data as a plurality of records and a storage control unit for controlling data transfer between said external storage unit and said central processing unit, and said storage control unit having memory means for temporarily storing data as a plurality of records, wherein

• upon reception of a search command from said central processing unit, said storage subsystem supplies a signal to said central processing unit, said signal indicating a termination of operation of said storage subsystem with said central processing unit, disconnects said central processing unit, and performs a search of search data in said memory means.

A data searching method for a storage control unit connected to an external storage unit for storing data as a plurality of records, each record having a count field, a key field, and a data field, and to a central processing unit, said storage control unit having a cache memory and controlling data transfer between said external storage unit and said central processing unit, wherein

• upon reception of a key search command from said central processing unit, said storage control unit issues a quasi completion report to said central processing unit, disconnects said central processing unit, and executes a key field comparison with a search track having a plurality of said records in said cache memory, and if a condition of said key field comparison is satisfied, said storage control unit issues a completion report to said central processing unit to terminate a key search, and if the condition of said key field comparison is not satisfied, said storage control unit executes said key field comparison with the next track.

A storage control unit connected to an external storage unit for storing data as a plurality of records and to a central processing unit, said storage control unit controlling data transfer between said external storage unit and said central processing unit, wherein

• said storage control unit has a controller for disconnecting said storage control unit from said central processing unit after receiving a search command from said central processing unit when said storage control unit searches data with respect to a plurality of said records.

A storage subsystem connected to a central processing unit, said storage subsystem having an external storage unit for storing data as a plurality of records and a storage control unit for controlling data transfer between said external storage unit and said central processing unit, wherein

• said storage subsystem has a controller which operates such that upon reception of a search command from said central processing unit, said storage subsystem supplies a signal to said central processing unit, said signal indicating a termination of operation of said storage subsystem with said central processing unit, disconnects said central processing unit, and performs a search of search data in a cache memory having a plurality of said records.

A storage control unit connected to an external storage unit for storing data as a plurality of records, each record having a count field, a key field, and a data field, and to a central processing unit, said storage control unit having a cache memory and controlling data transfer between said external storage unit and said central processing unit, wherein

• said storage control unit has a controller which operates such that upon reception of a key search command from said central processing unit, said storage control unit issues a quasi completion report to said central processing unit, disconnects said central processing unit, and executes a key field comparison with a search track having a plurality of said records in said cache memory, and if a condition of said key field comparison is satisfied, said storage control unit issues a completion report to said central processing unit to terminate a key search, and if the condition of said key field comparison is not satisfied, said storage control unit executes said key field comparison with the next track.

A data transfer method for a data transmission line between a storage control unit and a central processing unit, said storage control unit being connected to an external storage unit for storing data and controlling said external storage unit, and said central processing unit issuing an input/output command to said storage control unit, wherein

• when said central processing unit transmits a search request signal, said storage control unit transmits a termination signal to said central processing unit, said termination signal indicating a termination of operation of said storage control unit with said central processing unit, and disconnects said data transmission line.

A data transfer method for a data transmission line between a storage control unit and a central processing unit, said storage control unit being connected to an external storage unit for storing data and controlling said external storage unit, and said central processing unit issuing an input/output command to said storage control unit, wherein

• when said central processing unit transmits a search request signal, said storage control unit transmits a termination signal to said central processing unit, said termination signal indicating a termination of operation of said storage control unit with said central processing unit, said storage control unit or said central processing unit disconnects a logical connection between said storage control unit and said central processing unit, and thereafter said storage control unit transmits a completikon report to logically connect said central processing unit to said storage control unit.

A data transfer method for a data transmission line between a storage control unit and a central processing unit, said storage control unit being connected to an external storage unit for storing data and controlling said external storage unit, and said central processing unit issuing an input/output command to said storage control unit, wherein

• when said central processing unit transmits a key search request, said storage control unit transmits a quasi completion report, intercepts data transfer over said data transmission line between said central processing unit and said storage control unit, and after completion of a key search by said storage control unit, said storage control unit transmits a completion report to resume data transfer over said data transmission line.