Patent ID: 7114049
Filing Date: 2006-09-26
Classification: G06F

Abstract:
1. A storage system comprising: a first computer system configured to receive storage access requests from one or more user systems and to process the storage access requests; a first data storage system operative with the first computer system to satisfy received storage requests, the first data storage system comprising a plurality of data volumes including a primary volume and a primary difference volume; a second computer system; a second data storage system operative with the second computer system and comprising a plurality of data volumes including a secondary volume and a secondary difference volume; a first communication path between the first and second computer systems; and a second communication path between the first data storage system and the second data storage system, the first data storage system configured to perform steps of storing data received from the first computer system to the primary volume and communicating blocks of data from the primary volume to the second data storage system, and in response to receiving a first command from the first computer system: the second computer system configured to receive a second command from the first computer system and in response to take over receiving and processing of storage access requests whereby the first computer system ceases to process storage access requests, the second data storage system configured to selectively access first data stored on the first data storage system in order to service a storage access request received by the second computer system and further configured to store the first data in the second data storage system.