Patent ID: 7685189
Filing Date: 2010-03-23
Classification: G06F

Abstract:
1. A method for preserving application data on a storage device of a system at the approximate time of a failure of the system by determining changed application data blocks of a storage device since the last backup where the application data is stored as backup data, said application data being associated with an application program and located on said storage device, said method comprising: determining the changed application data blocks on the storage device as a function of the application data and the backup data, wherein said determining comprises: in response to the received indication that the system failure has occurred, generating file change data for each file of the application data on the storage device of the system as a function e-f corresponding to the determined changed application blocks on the storage device of the system and file system metadata, wherein said the file system metadata includes information about˜file system writes operations to the storage device since the last backup, said file change data indicating the blocks of each file˜that have been modified on the storage device of the system since the last backup of the application data was stored on the backup server; generating a first file difference record for each file of the application data on the storage device of the system including as a function of the generated file change data, said first file difference record indicating the modifications to each file of the application data on the storage device since the last backup of the application data was stored on the backup server; transferring the generated first file difference record to the backup server, said backup server applying the first file difference record to the last backup of the application data stored on the backup server to generate a replica of the application data on the backup server, said backup server retaining the first file difference record; receiving a second file difference record for each changed file corresponding to the generated file change data, the second file difference record indicating changes between the transferred first file difference record corresponding to the application data on the storage device and the replica; and applying the second file difference record to the application data such that application data on the storage device corresponds to the state of replica data.