Abstract: The present intention is a disk control device and control method sharing an FBA disk unit between mainframes (global servers) using a variable-block format and open servers using a fixed-block format and which are host devices. The first host device using the variable-block format and the second host device using the fixed-block format connect individually through a dedicated first channel adapter and second channel adapter, respectively. The disk control device includes a conversion function between the variable-block format of the first host device and the fixed-block format of the disk unit. In addition, the second channel adapter includes a conversion function between the fixed-block format of the second host device and the variable-block format of the disk control device. These functions enable the first host device using the variable-block format and the second host device using the fixed-block format to share the resources of the disk unit.

Abstract: The present invention is a disk control device and control method sharing an FBA disk unit between mainframes (global servers) using a variable-block format and open servers using a fixed-block format and which are host devices. The first host device using the variable-block format and the second host device using the fixed-block format connect individually through a dedicated first channel adapter and second channel adapter, respectively. The disk control device includes a conversion function between the variable-block format of the first host device and the fixed-block format of the disk unit. In addition, the second channel adapter includes a conversion function between the fixed-block format of the second host device and the variable-block format of the disk control device. These functions enable the first host device using the variable-block format and the second host device using the fixed-block format to share the resources of the disk unit.

Abstract: The present invention is a disk control device and control method sharing an FBA disk unit between mainframes (global servers) using a variable-block format and open servers using a fixed-block format and which are host devices. The first host device using the variable-block format and the second host device using the fixed-block format connect individually through a dedicated first channel adapter and second channel adapter, respectively. The disk control device includes a conversion function between the variable-block format of the first host device and the fixed-block format of the disk unit. In addition, the second channel adapter includes a conversion function between the fixed-block format of the second host device and the variable-block format of the disk control device. These functions enable the first host device using the variable-block format and the second host device using the fixed-block format to share the resources of the disk unit.

Abstract: One CKD track on a direct-access storage device is divided into a plurality of fixed-length FBA blocks, only a home address HA of the CKD track and a record R0 having a CKD format are recorded in the leading FBA block, and each field (a COUNT field, KEY field and DATA field) of records R1, R2, . . . having the CKD format is recorded in the other FBA blocks. This arrangement is such that even if a format-write processing instruction for format-write from the record R1 is received from a host device, a disk control unit will not read the FBA block of HA/R0 out to a cache memory and will read out only FBA blocks from record R1 onward. As a consequence, write processing from record R1 onward can be performed in memory with ease and format-write processing can be executed at high speed.

Abstract: An ID portion indicating the corresponding relationship between the number of a record contained in an FBA block and the position of the record is provided at the beginning of the FBA block. When a seek command has been issued by a host apparatus in the CKD format, a device adapter obtains the FBA block number corresponding to the parameter value (CCHH) of a head positioning command and positions a head at the FBA block of this number. Next, the device adapter obtains the FBA block number corresponding to the parameter value (sector value) of a set-sector command, reads one CKD track of blocks from the FBA block designated by the FBA block number and develops these blocks in a cache memory. A channel adapter searches the cache memory for a commanded record by referring to the information in the ID portion.

Abstract: In a disk drive and a method for retrying to check data in the disk drive, a magnetic disk subsystem comprises a magnetic disk control unit and a drive module. The magnetic disk control unit is provided with a unit for controlling data check retry sequence which has a dummy write control unit. The drive module is provided with heads and a positioning unit. When the data read from the medium contain error, the above unit controls the data check retry sequence in order to read again the data using the same head. The dummy write control unit seeks a dummy write cylinder during the data check retry sequence, effects the dummy writing, seeks the original cylinder again, and reads the data again.