Patent ID: 6397351
Filing Date: 2002-05-28
Classification: G06F

Abstract:
A method for restoring a backup dataset in a storage system, where contents of the backup dataset comprise contents of a corresponding original dataset upon creation of the backup dataset and where changes to the original dataset received by the system after creating the backup dataset are logged by the system in a change log, the method comprising:in response to unavailability of the original dataset, commencing application of the logged changes to the backup dataset; and during the application of the logged changes to the backup dataset, receiving one or more requests to access one or more subparts of the original dataset, and responsive to each request, for each subpart: determining whether the change log contains any changes not yet applied to the subpart of the backup dataset; and satisfying the request by: if the log contains one or more changes not yet applied to the subpart of the backup dataset, providing an output of the subpart from the log the output comprising a most recent one of the changes not yet applied; if the log does not contain any logged changes not yet applied to the subpart of the backup dataset, providing an output of the subpart from the backup dataset.