Stellar Smart is a utility that acts as an "early warning system" for pending hard disk problems. The system is based on Self-Monitoring Analysis and Reporting Technology (S.M.A.R.T). The hard disk's integrated controller works with various sensors to monitor various aspects of the drive's / disk's performance and determines from this information if the disk is behaving normally or not. File system data structures of a drive have suffered serious corruption or overwriting and data recovery software cannot scan such drives.