Mechanism for incremental backup of on-line files

摘要

A backup mechanism enables incremental backup operations for on-line files of a computer system having an archive bit attribute associated with each file. The mechanism comprises an archive bit change number (ABCN) attribute that is also associated with each file and that is manipulated by a file system of the computer to reflect a correct value of the archive bit when the file is modified during a current backup operation. The ABCN attribute is incremented each time the file is modified to ensure that the file is accurately copied to secondary backup storage during a subsequent incremental backup operation. The mechanism thus enables reliable on-line file modifications which, in turn, substantially increases the efficiency of the computer system.