Abstract: A system and method for controlling a backup operation to backup data from a source device to a backup storage device are described. Backup software creates checkpoints during the backup operation. Each checkpoint represents a point from which the backup operation can be re-started in case of failure. The backup software enables an administrator to specify a desired time interval between the checkpoints. The backup operation is performed using a backup protocol which uses a transfer frame size to determine when to create each checkpoint. The backup software translates the checkpoint time interval specified by the administrator into an appropriate transfer frame size in order to achieve the desired checkpoint time interval. The transfer frame size may be dynamically adjusted between each checkpoint.