Patent ID: 7801867

Claim:
A method for generating consecutive replicas at a backup server for application data located on a storage device associated with an application server, said backup server and said application server being coupled via a logical communication connection, said method comprising: providing an application server having application data stored on a storage device; providing an backup server; coupling the application and backup servers via a logical communication connection; receiving at the backup server a first replica of the application data from the application server via the logical communication connection, said application data being located on the storage device associated with the application server, said first replica being a copy of the application data stored on said storage device at a particular point in time and representing a first state of application data, said first replica being stored on the backup server; receiving at the backup server first file change data from the application server via the logical communication connection, said first file change data indicating the blocks of a file associated with the application data that have been changed on the storage device associated with the application server since the particular point in time when the first replica of the application data was stored on the backup server; receiving at the backup server a first file difference record from the application server via the logical communication connection, said first file difference record containing data changes between a second state of the application data located on the storage device associated with the application server and the first replica stored on the backup server; and generating, at the backup server, a second replica from the first replica and the received first file difference record by creating a second replica from the first replica data and applying the received first file difference record to the first replica data in the second replica such that said second replica is in a state corresponding the second state of the application data, wherein the first replica is preserved on the backup server; and deleting at the backup server the first file difference record, said deleting occurring after the first file difference record has been applied to the first replica to generate the second replica.