Sunday October 09, 2016

What SMART Stats Tell Us About Hard Drives

Backblaze has a piece on what SMART stats they use to predict whether a drive will fail or not. These would include attributes such as 5 (reallocated sectors count), 187 (reported uncorrectable errors), and 198 (uncorrectable sector count).

Having a given drive stat with a value that is greater than zero may mean nothing at the moment. For example, a drive may have a SMART 5 raw value of 2, meaning two drive sectors have been remapped. On its own such a value means little until combined with other factors. The reality is it can take a fair amount of intelligence (both human and artificial) during the evaluation process to reach the conclusion that an operational drive is going to fail. One thing that helps is when we observe multiple SMART errors.