In response to a command including file extent information defining a file area received from a host processor, a disk cache processor stores the file extent information in an extent table and reserves a corresponding area in a disk cache buffer. In response to a WRITE command, the processor stores the data in the corresponding reserved area of the disk cache buffer and sets a write flag of the corresponding entry of a cache directory. When the processor is idling, it writes to a disk unit the data in the disk cache buffer which has not yet been written to the disk unit, and resets the corresponding write flag. In response to a command received from the host processor which has file extent information and designates a logical termination of a program, the processor writes all of the not-yet-written data which corresponds to the file area indicated by the extent information. When an error is caused during data write to the disk unit, the processor stores corresponding error status information into an error log table such that it corresponds to the extent information in the extent table. After data write into the designated area is terminated, the processor fetches the error status information for this file area alone and transfers the fetched information to the host processor.
A method of restoring write data in a disk cache system includes the steps of providing a host, a disk drive having a plurality of tracks including a plurality of records, a cache memory, a nonvolatile memory storing a directory which controls storing of tracks within the nonvolatile memory, and a disk controller. The disk controller writes tracks of data from the disk drive, including records addressed by a read command sent from the host, into the cache memory. The disk controller also writes tracks of data, including records updated by the host, into the nonvolatile memory in response to a write command sent from the host, and restores the records updated by the host to the disk drive during an idle time of the disk drive. A record in the nonvolatile memory is updated in response to the write command sent from the host. A start address and an end address of a record to be restored to the disk drive from the nonvolatile memory are updated in response to an address of a record updated by the host. Restoring of the record to the disk drive from the nonvolatile memory is performed in response to receipt of the start address and the end address of the record to be restored to the disk drive from the nonvolatile memory.
A disk storage system, provided with a disk as an information storage unit, having information of defects relating to the disk. The disk storage system includes a disk drive unit for driving the disk in its operable state, a memory unit different from the disk for storing information of defects relating to the disk, and a disk controller for detecting defects relating to the disk and for controlling the disk drive unit and the memory unit to store information of the defects relating to the disk into the memory means and to access the stored information of defects relating to the disk.
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.
A disk drive system includes a disk controller system having separate head positioning and data transfer subsystems and supporting up to four disk drives, two of which may be removable, portable drive units and two of which may connect through a standard ST506 interface. The removable disk drives incorporate a read and write protected data cylinder for storing information such as the maintenance history of the drive, and a read only cylinder for storing a unique serial number as well as other write protected data. The system also features a high capacity, high speed sector buffer which allows continuous transfers of data to or from noninterleaved sectors and supports concurrent disk and system accesses.
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.
