Digi-data Corporation

Kenneth Lewis Willis

Raymond Duchesne

A 'Logging' method and apparatus is provided to protect control unit cached data not yet written to backing storage disk drives. This recording mechanism copies 'WRITE DATA' to a log at a target logically external or physically external to storage control units which are connected to a common storage pool and constitute a set. Upon failure of one of the set of control units, the &#x201c;Log&#x201d; information is available to insure that pending &#x201c;write&#x201d; data is written to the proper location on the disk drives of the storage pool upon a recovery action. One of surviving members of the set assumes control of the storage managed by the failing control unit by utilizing the recorded information to insure that data not written to backing storage (disks) up to the point of failure is then written to the disk backing storage. The surviving member of the set recovering the failing control unit storage (disk set) ownership effects a &#x201c;flush&#x201d; of (WRITE) the Journaled WRITE DATA to the backing storage disk drives before allowing normal operations to proceed.

Growing community of inventors

Westminster, CO, United States of America

Kenneth Lewis Willis