Some hard drive crashes are random but most are predictable. That’s because almost all modern drives implement a monitoring technology called S.M.A.R.T (Self Monitoring Analysis and Reporting Technology) that continuously passes readings on the hard drive condition to the computer’s BIOS. Up to 30 drive parameters can be monitored by SMART including read and write error rates, seek error rate, spin up time, temperature and more.
To analyze this mass of data you need a special hard disk health monitoring program. Such programs can give you valuable advance warning that your hard drive is about to fail. This should give you time to backup your critical data and start looking for a replacement drive.
Most of these monitoring programs are commercial products with some selling for up to $199, however there are several capable free programs available.
PassMark DiskCheckup  is a commercial product but is free for personal use. One of its strong points is the ability to monitor changes in each SMART parameter over time and use this to predict the TEC (Threshold Exceed Condition). That is, the time when the parameter being measured will drop to below the acceptable level. As well as predicting a future failure date DiskCheckup can also alert the user via popup or email when this has actually occurred.
It all sounds very nice but such predictions are quite fuzzy, so they are at best a guide. Also, predictions can only be made if a trend is measured. Most drives have no such orderly trend. That’s why DiskCheckup almost always indicates "N.A" for the TEC. Besides, to measure a trend the product needs to be always running and not all users want that.
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