Patent ID: 7228538

Claim:
A method for updating code in a first and second controllers, wherein the first and second controllers are capable of accessing storage regions in a storage device, and wherein host systems communicate Input/Output (I/O) requests directed to the storage regions to one of the first and second controllers, comprising: providing a storage region assignment of storage regions assigned to the first and second controllers, wherein commands to one storage region are directed to the first or second controller to which the storage region is assigned; receiving a code update at the first controller; communicating to the second controller information on the storage regions assigned to the first controller according to the storage region assignment in response to receiving the code update; enabling the host systems access to revised storage region assignment information to cause the host systems to send I/O requests to storage regions assigned to the first controller according to the storage region assignment to the second controller during the code update at the first controller; disabling access to the first controller; and applying the code update to the first controller, wherein the second controller receives commands directed to the storage regions assigned to the first controller during the code update to the first controller.