STORAGE SYSTEM AND METHOD OF OPERATING THEREOF

摘要

There are provided a storage system, storage control unit, volatile cache memory and method of operating thereof. The storage system comprises a permanent storage subsystem with internal cache memory, a storage control unit and a volatile cache memory operable to cache "dirty" data pending to be written to the permanent storage subsystem and to enable, responsive to at least one command by the control storage unit, destaging said "dirty" data or part thereof to the permanent storage subsystem. The volatile cache memory is further operable to cache data destaged to the permanent storage subsystem whilst keeping this data as non-erasable thus giving rise to "washed" data, and, responsive to at least one command by the storage control unit, to facilitate reclassification of the "washed" data or part thereof into erasable data thus giving rise to "clean" data. The storage control unit is further operable to determine achievement of a "writing criterion", to provide, upon achieving, at least one command to the permanent storage subsystem requiring flushing destaged data or part thereof from the internal cache memory to the non-volatile storage medium, and to provide at least one command to the volatile cache memory requiring reclassification of the "washed" data or a respective part thereof into the "clean" data. The storage system further comprises a non-volatile data storage unit operatively coupled to the volatile cache memory, and an uninterruptible power supply (UPS) operable to maintain the volatile cache memory, the storage control unit and the non-volatile storage unit in an operational state for a period of time in the event of a power failure and to enable storing "dirty" data and "washed" data in the non-volatile data storage unit.