Do SMART values have any sense at all?

Question

Is it possible to understand SMART values somehow?

Here is an example of values shown for one of my drives:

Following questions arise:

1. If Reallocated Sectors Count is 2 and threshold is 36, then why is marked with red? Threshold is not exceeded yet!
2. What is FB3? From hex it is 4019, i.e. neither 36 nor 2. Where it took the values then?
3. Current Pending Sector Count is 100 and threshold is 0. Threshold is exceeded. Why is it marked with yellow then, not red?
4. Why are there so much 100 values? Looks like it is stub value. How it can know status then, if the value is stubbed?
5. What is B? From hex it is 11. Neither 0, nor 100. Where it too value then?

So, the only understandable value is the color of knob at left, while all other values are filled with delirium. Is it possible to understand here something?

Note that by some reason, this delirium is repeated from one SMART application to another.

Answer 1

Current, Worst, Threshold are normalized values as opposed to Raw Values.

1. HDD has 0xFB3 (4019) reallocated sectors, which yields a normalized current score of 2, way below the threshold of 36.
2. Raw Values as returned by internal sensors/counters.
3. HDD has 0xB (11) sectors pending reallocation.
4. Good Question! My guess is that these attributes might not be critical so manufacturer does not bother to normalize them properly.

Answer 2

1. Because the actual value of reallocated sectors is 4019 (it is the raw value that represents the count of the bad sectors that have been found and remapped), which exceeds flag value 2 (which is 36) by a lot.

2. FB3 is 4019 in HEX.

3. Because the actual value (hex:B = 11) is not close to 100, more specifically, in your case, 100-11 is not close to 0, yet. See 5. (related).

4. They are chosen by the manufacturer.

5. Some values are set as max by default and actually decrement or are based on differences from 100 (or other values). See 3. (related).

Basically, it's the raw values that in many cases should interest you a lot.

The conclusion is that your HDD has way too many reallocated sectors and a few uncorrectable ones. you should consider replacement.

Here's some good info on the subject.

As for values:

• Current/Normalized: This is the above value normalized so a higher value is always better for most of the values (total R/W is an exception example). So 95 in spin-up time is better than 94. This also can vary from one manufacturer to another, which can introduce confusion.

• Worst: The worst normalized value that your HDD had in the past (values like 99 or 199 are common default settings).

• Threshold: When the normalized value is lower than this value the HDD is likely to fail. Note your 36 value compared to the Raw. That's why it's red.

• Actual/Raw Value: This is the raw value that the controller reports. It's most of the time an easy to understand value, but it can also vary from one manufacturer to another.