Data storage system using 3-party hand-off protocol to facilitate failure recovery

A data storage system comprising:

• a) a disk drive for storing a plurality of data;
• b) a first memory for storing a plurality of cache data;
• c) a second memory for storing metadata associated with stored data including said cache data and said data;
• d) a first type processing module for partially executing a first group of data storage operations and for handling said cache data;
• e) a second type processing module for partially executing a second group of data storage operations and for managing said metadata;
• and
• f) a third type processing module for partially executing a third group of data storage operations and for handling said data and said cache data, wherein at least two of said first, second, and third type processing modules are required to cooperate in a hand-off manner to fully execute any one of said data storage operations, and wherein if an abnormal state arises when attempting to fully execute a particular data storage operation, a particular module of said first, second, and third type processing modules involved in executing said particular data storage operation detects said abnormal state and proceeds to recover from said abnormal state.

A method of responding to a plurality of requests from one or more external systems received by a data storage system, comprising:

• a) accessing each request at said data storage system comprising a first type processing module for partially executing a first group of data storage operations, a second type processing module for partially executing a second group of data storage operations, and a third type processing module for partially executing a third group of data storage operations;
• b) in response to each request, fully executing a corresponding one of said data storage operations by using at least two of said first, second, and third type processing modules cooperating in a hand-off manner;
• and
• c) if an abnormal state arises during said b), detecting said abnormal state and proceeding to recover from said abnormal state by using a particular module of said first, second, and third type processing modules involved in executing said corresponding data storage operation.