What SMART Stats Tell Us About Hard Drives

Megalith

Megalith

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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.
 
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I've never trusted S.M.A.R.T. stats, and with dozens of drives over the past decade that fail outright for whatever reason - because S.M.A.R.T. status remains clean or "green" as the indicators usually are - I've learned that it too can fail in the actual prediction of overall failure. There's nothing more frustrating that using some type of diagnostic hardware or software to figure out why a given drive fails and all you get back is basically 'We can't find anything wrong..." sort of response and yet the drive simply doesn't work anymore.
 
I always read BackBlaze articles and this one provides some good troubleshooting information. They provide proof that monitoring S.M.A.R.T. stats is the smart thing to do.
 
Tiberian said:
I've never trusted S.M.A.R.T. stats, and with dozens of drives over the past decade that fail outright for whatever reason - because S.M.A.R.T. status remains clean or "green" as the indicators usually are - I've learned that it too can fail in the actual prediction of overall failure. There's nothing more frustrating that using some type of diagnostic hardware or software to figure out why a given drive fails and all you get back is basically 'We can't find anything wrong..." sort of response and yet the drive simply doesn't work anymore.
Click to expand...

Or worse, it throws smart errors but continues to work for months or years.
It is just another tool. I don't trust the "all is well" , but I would rather not risk disregarding "this drive should be replaced".
 
I just want a S.M.A.R.T tool to actually give me readable and consistent error counts between drive models and manufacturers.

I have yet to see any that do this. Even the diagnostics from the drive manufacturers themselves aren't consistent.

And good luck finding definitions of the different names for the data.
 
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