摘要 |
A disk cache operation which was optimized so as to adapted to an operation form of the user and a disk array is executed. A cache mechanism is provided for each of two sets of controllers and can be made operative in either one of the reliability significance mode for storing the same data into each system, the performance significance mode for independently storing data every system, and the average mode of both of said modes. A cache process in which a disk array which operates in RAID0, RAID1, RAID3, or RAID5 is set to a target is efficiently executed. Effective data is prepared on a cache block so as to enable an access like RAID3 such that a parity can be calculated without needing to read the disk even in the operation of RAID5. |