A data backup system for backing up a data file from a source device having a source processor and an input device to a target device having a target processor and a database over a communication network. The source processor determines whether the data file has been modified, and if so, determines the modified data block(s). The modified data block(s) are transmitted from the source processor to the target processor over the communication network. The target processor receives the modified data block(s) from the source device over the communications network, and uses the modified data block(s) to construct the data file, and to store the data file on the database. Concurrently, it is determined if the input device is active at any time during the backup process, and if so, the backup processing is interrupted until the input device has been inactive for a predetermined period of time.