USER-LEVEL BACKUP FILE SYSTEM

摘要

A backup file system which can be used without modification of application programs, the operating system, or the hardware. The backup file sys tem is implemented by means of a dynamically-linkable replacement library and user-level processes on a primary computer system and a backup computer system. The dynamically-linkable replacement library has the same interfaces as a standard dynamically-linkable library of file operations. The functions in the replacemen t library perform the same file operations as their counterparts in the standard l ibrary; in addition they send messages specifying the just-performed operation to a user-level process on the backup computer system. The user-level process execute s the operation specified in the message on a backup file in the backup computer syste m. The files to be backed up are specified by identifying subtrees in the namespace of the primary file system; the subtrees make up a user-defined namespace. The back up file system is made fault tolerant by the use of monitor processes which monitor the backup computer system and the processes of the backup file system and deal with failures as required to keep the backup file system operating.