Commvault Systems, Inc.
FAST RECALL OF LARGE ARCHIVED FILES

Abstract:

Large files may be archived on secondary storage in a multitude of extents or data blocks. The system intercepts a read operation on a stub file and determines which extent(s) correspond(s) to the data being requested. The system recalls the user-requested extents and determines which extents may be recalled soon. A queue may be used to organize the order of the recall requests based on the type of priority of the request. As the extents are received and processed, they are stored into the stub file for user access before the remainder of the archived file is recalled. The routines performed may be implemented using data structures such as bitmaps and priority queues. The system may use the stored bitmap tables and queues to resume an earlier failed file recall.