Patent ID: 6983353
Filing Date: 2006-01-03
Classification: G06F

Abstract:
1. A method for maintaining data consistency in a group of logical devices formed in a disk storage system wherein each logical device responds to read and write commands issued from a host by performing a commanded operation and by transferring a message to the host indicating the outcome of the commanded operation, said method comprising the steps of: A) establishing a plurality of the logical devices as a local consistency group with a reject window having an open state that extends for a predetermined interval and a closed state, B) blocking, at a control for each logical device, only the processing of a write command directed to a logical device in the defined consistency group while the reject window is in the open state whereby commanded read operations to each logical device in the consistency group are processed even when the reject window is in an open state, and C) in response to said blocking and receipt of a write command, generating a predetermined return message to the host indicating a blocked write command for a response thereto.