Patent ID: 7137033

Claim:
A method comprising: maintaining in a first data structure in a first storage controller, a first index for a first write data task for writing data to a storage device coupled to the first storage controller and for writing data to a storage device coupled to a second storage controller, wherein the first write data task comprises a first sequence of data writing subtasks in which each subtask has a sequence number identifying the position of the subtask in the sequence of subtasks of the first write data task and wherein the first index identifies the sequence number of the next subtask in sequence to be sent by a first processor of the first storage controller to a second processor of the first storage controller; adding a subtask of said first sequence of data writing subtasks to a queue; comparing the sequence number of a subtask in the queue to the index of the first data structure; and if the subtask in the queue has the sequence number identified by the index, sending the subtask to a second processor of the first storage controller to generate a write command to the second storage controller.