This is the software publisher's description. 

Running quietly in the background, the new version O&O DriveLED monitors hard disks, alerting users to potentially disastrous hard disk crashes. Unique to this version of O&O DriveLED is its utilization of internally monitored hard disk information, or S.M.A.R.T. (Self Monitoring, Analysis, and Reporting Technology). By analyzing this internal information from hard disks, users can get a detailed display showing the hard disk's most important parameters, from the number of system starts to the current temperature. O&O DriveLED can also conduct S.M.A.R.T. self tests, allowing users to ascertain the "health" of their hard disk volumes.

Additionally, the O&O DriveLED ControlCenter desktop interface provides a complete overview of all local and network drives connected to the system and monitors all read and write access to those drives. Should an O&O DriveLED alert occur, users would be instantly advised through the ControlCenter to make a back-up of their important files before a system crash makes them irrecoverable.