Abstract: A buffer memory capable of storing contents of a plurality of tracks of a disk volume is provided in a disk controller or a disk drive, and in dump processing requested by a higher rank unit (CPU) to the disk controller, the data is immediately transferred from the buffer memory if the data to be dumped is present in the buffer memory, and if the data to be dumped is not present in the buffer memory, dump prefetching into the buffer memory is started and the execution of the dump processing is interrupted so that an on-line input/output operation other than the dump processing is accepted. When the dump prefetching into the buffer memory is over, the interrupted dump processing is resumed.

Abstract: In an information processing system having a data processing apparatus, a control unit for a cache memory, and a storage unit for storing a record, respectively interconnected together, wherein when the control unit receives from the data processing apparatus a write request for a record to be written and if the record to be written is not being stored in the cache memory, the control unit receives a data to be written in the object record from the data processing apparatus and stores the received data in the cache memory. After notifying the data processing apparatus of a completion of a data write process, the control unit checks if the object record in which the data stored in the cache memory is being stored in the storage unit, if the object record is being stored in the storage unit, the data in the cache memory is written in the storage unit, and if not, the data in the cache memory is not written and such effect is notified to the data processing apparatus.

Abstract: A buffer memory capable of storing contents of a plurality of tracks of a disk volume is provided in a disk controller or a disk drive, and in dump processing requested by a higher rank unit (CPU) to the disk controller, the data is immediately transferred from the buffer memory if the data to be dumped is present in the buffer memory, and if the data to be dumped is not present in the buffer memory, dump prefetching into the buffer memory is started and the execution of the dump processing is interrupted so that an on-line input/output operation other than the dump processing is accepted. When the dump prefetching into the buffer memory is over, the interrupted dump processing is resumed.

Abstract: An external memory device subsystem and a data recording device, which issue a command specifying previously a plurality of tracks in a rotary type memory device prior to a read or write instruction issued from the data processing unit of higher rank to the rotary type memory device through a control unit; select continuously the plurality of tracks previously specified, at executing a read or write command after the execution of the command; and in this way can read/write continuously without wait time for rotation a plurality of tracks distant from each other within the same cylinder.

Abstract: A method of emulating an original record format for a new rotating storage device, including the steps of;(a) determining an original angular position (.alpha.) of a record according to a first recording format;(b) determining a desirable angular position (.beta.) for recording according to a second recording format having a higher recording density than that of the first recording format;(c) subtracting the desirable angular position from the original angular position to obtain a difference between the angles (.alpha.-.beta.); and(d) incrementing a gap length immediately before the data field of the record when the angular position exceeds a value corresponding to one unit of segment.

Abstract: In a control unit having a external storage device, a method for selecting a loading method of data stored in the cache memory into the cache memory in accordance with an access pattern to the data, and an apparatus therefor are disclosed. The selection of the loading method is selection of control mode or procedure in accordance with the loading method, and it is attained by a learn function.

Abstract: In a data processing system having a first external memory, a second external memory, and a control memory for storing information on data renewals in the first external memory, a system and a method provide for back-up operations in parallel with ordinary data processing, including dump processing in which renewed data parts in the first external memory are copied as backup data into the second external memory with reference to the contents of the control memory.

Abstract: Buffers are separately provided for a region for non-sequential transfer and for a region for sequential transfer in each one of the disk units. A director sends a message to inform at least one of the disk units whether transfer of data the respective disk units are to make is sequential or non-sequential. When the disk unit receives a non-sequential transfer request, it uses the buffer region for non-sequential transfer to transfer data requested by the director and when it receives a sequential transfer request, it uses a plurality of buffer regions for the sequential transfer. Thus, data transfer is performed between a host device and that disk unit.

Abstract: An external memory device subsystem and a data recording device, which issue a command specifying a plurality of tracks (surfaces) in a rotary type memory device prior to a read or write instruction being issued from the data processing unit of higher rank to the rotary type memory device through a control unit; selects sequentially the plurality of individual tracks (surfaces) previously specified when executing a read or write command after the receipt of the command; and in this way can read/write continuously without wait time interruptions when data is discontinuous.

Abstract: An interrupt control system having a plurality of access paths includes a control memory for storing control information for controlling all of the access paths. When an error occurs on a path, a control unit controlling the respective access paths refers to and updates the control memory to execute a channel reconnection without using the path on which the error has occurred, and then executes a retry command to carry out an error recovery operation.

Abstract: A computer system having a disk cache unit between a disk unit and the main storage unit. Ordinarily, the data transfer processing is carried out between the disk unit and the disk cache unit and between the disk cache unit and the main storage unit in this case. The present invention is characterized by enabling these two data transfer operations to be executed in parallel and to prevent a director from becoming the bottleneck of the processing due to the concentrated processing requests. For this purpose, the present invention provides for conducting a data transfer between the disk cache unit and a disk unit while a data transfer is taking place between the main storage unit and the disk cache unit. The director is configured, for example, with two data transfer controlling systems and two data transfer units for carrying out data transfer according to instructions for the two data transfer controlling systems.

Abstract: A control system for a disk cache memory is disposed between a main memory unit and a disk unit for storing a record of data from the disk unit. The control system is designed such that when an input/output instruction is issued from a CPU while data loading is being performed from the disk unit to the cache memory, it interrupts the data loading once so that an input/output instruction from the CPU can be executed, thereby considerably reducing the time of wait for execution of the input/output instruction.

Abstract: A method of controlling a magnetic disc apparatus. When a format writing is performed on a designated track portion, information of the location of the latest format writing record is read out from a control table storing information of the locations of the records of the format writings performed already to be compared with the information of location of the designated track portion where the format writing is to be currently performed. In dependence on the result of the comparison, it is decided whether erasing operation for the remaining track portions following the designated one is necessary or not. When decision is such that the erasure is necessary, erasing operation is performed for the remaining track portion in succession to the format writing on the designated track portion. Otherwise, the erasing operation is not performed for the remaining track portion, and information of the location of the record resulting from the format writing is subsequently stored in the control table.

Abstract: When a disk controller receiving an access from a host computer to a disk device is connected with a disk connection device, if a relevant disk is used by another disk controller, positioning data for seek, set file mask and set sector are queued in a common memory. When the relevant disk becomes free, the disk controller reads the queued information and requires the disk device for positioning. A request of a reconnection with the host computer is issued from the disk controller informed by the disk unit, which has finished positioning at the position specified by the positioning data, search of an aimed record and a read/write operation of transmitted data are effected without any new intervening of an access program of the host computer.

Abstract: A method for controlling to keep off defects in a magnetic disk apparatus while has a plurality of magnetic disks and defect position information is recorded in each of tracks on each magnetic disk to keep off a defect in writing records in each track. Positional information about defects on all the tracks belonging to a cylinder of the magnetic disk apparatus is recorded in each of the tracks, and records are written in each of the tracks while keeping off the defects on the basis of the recorded positional information about the defects.

Abstract: In a magnetic disk unit for recording/reproducing data onto/from a disc by means of a magnetic head on the basis of a seek command and a recording/reproducing command received from a host processor, the execution of the data reproducing command for the disk is started upon detection of a state that the magnetic head has sought on a desired track to an extent that the centering state is still unstable but the data can be reproduced, and the execution of the data recording command is started upon detection of a condition that the magnetic head has reached the stable centering state on the desired track after the detection of the reproducible state.

Abstract: The present invention relates to a computer system having a disk cache unit between a disk unit and the main storage unit. Ordinarily, the data transfer processing is carried out between the disk unit and the disk cache unit and between the disk cache unit and the main storage unit in this case under control of a director. The present invention is characterized by enabling these two data transfer operations to be executed in parallel and to prevent the director from becoming the bottleneck of the processing due to the concentrated processing requests. For this purpose, the present invention provides for a data transfer between the disk cache unit and a disk unit while a data transfer is taking place between the main storage unit and the disk cache unit.

Abstract: There is disclosed an error recovery apparatus and method for a data processing system having (1) a peripheral unit, for instance, a magnetic disc unit, for storing data in a plurality of blocks each having a unique address, (2) a main memory for storing data read from the peripheral units, and (3) a controller for controlling the transfer of the data blocks from the peripheral unit to the main memory by execution of a single channel command word (CCW) chain. When an uncorrectable error occurs in the transfer of a second or subsequent data block of the plurality of data blocks (not the first data block), the processor produces a new CCW chain to re-read the data block in error in addition to all the data blocks subsequent to the data blocking error and store these data blocks in the memory under the control of the new CCW chain.