O&O DriveLED is a handy diagnostic tool which monitors your hard drives for signs of trouble. If, say, a drive's temperature is rising, or it's seeing more access errors, then you can easily find out. And that could help you spot an impending drive failure before it happens, giving you the time you need to back up your files and avoid data loss.
The core of the program is a simple compact toolbar which you can leave in a corner of your desktop. A status indicator shows your system drive temperature, while there are additional icons for each of your drives: these flash to indicate drive activity, and you can click them to open that particular drive in Explorer. Convenient tooltips reveal the free space on each drive, and you get additional shortcuts to your network and the Network Connections window.
When you need more in-depth information, though, DriveLED can quickly produce an in-depth report based on your drive's S.M.A.R.T. data (assuming the drive supports Self-Monitoring, Analysis and Reporting Technology, anyway - and most do).
Aside from basic information about your hardware - manufacturer, model, interface and so on - the report provides details on a host of statistics relating to your drive health: frequency of errors, number of uncorrected errors, calibration attempts, number of unstable sectors and more.
And if you're not quite sure how to interpret these, then don't worry, you don't have to be a hard drive expect to use the program. DriveLED takes all these statistics, weighs them up, and produces a single "Health" assessment which tells you how things really are.
If this warns you of problems then you'll need to make sure you're backing up critical files just as often as you possibly can, while also running reports more frequently to try and better understand what's happening.
But most of the time, fortunately, it'll just report your drive health as "OK", which means everything is fine. Of course it's still wise to run backups occasionally - there are many ways to lose your data, and DriveLED only checks for a few - but at least you can be sure that your drive itself is still healthy, with no sign of any impending problems.