Systems and methods for performing multi-threaded backups and restores. In one embodiment, a log is maintained to record the source of write commands, and the order in which blocks of data are written to a sequential storage device. The source identification of the write command may consist of such identifiers as a protocol dependent Host ID, the extended-copy-specification-defined List ID, a time stamp, and the size of the backup medium block written. The order in which the data is written to the backup medium can be identified with these same Host ID and List ID numbers. When it is desired to restore data corresponding to one of the threads, the desired blocks of data can be identified in the log, and the preceding blocks stored on the backup medium can be skipped.