Patent ID: 7499954
Filing Date: 2009-03-03
Classification: G06F,Y10S

Abstract:
1. A method for reintegrating a failed primary instance into a log shipping data replication system as a new secondary instance, comprising: maintaining a status of an operational mode of a primary instance in persistent storage; saving a takeover log position in persistent storage at a secondary instance during failover from said primary instance; truncating log data in a log file stored in persistent memory local to said failed primary instance that occurs after said takeover log position and prior to reintegrating said failed primary instance with a new primary instance, wherein the step of truncating includes removing any log data at the failed primary instance that is subsequent to the takeover log position; comparing said takeover log position with a final log position in persistent storage of said failed primary instance; reintegrating said failed primary instance after recovery as said new secondary instance in response to said comparison and without modifying contents of said failed primary instance; and determining failure of said failed primary instance was operating in a mode requiring an acknowledgment from said secondary instance of said log data received and written to persistent storage at said secondary instance before said failed primary instance allowed a post log write action in response to a successful writing of said log data to persistent storage in a log of said primary instance.