I have a 2TB internal hard drive that might be failing. It spends several minutes at 100% usage when I first turn it on since I installed Windows 10, and yesterday it reported a corrupted Recycle Bin.

I downloaded CrystalDiskInfo, and the pertinent information is reproduced below: enter image description here

In short, the Uncorrectable Sector Count count is 100, and this is a "caution"-level problem on the drive. No other labels are "caution".

I'm not sure what to make of the Current, Worst, and Threshold values. I know that some of their actual values vary by manufacturer, and I've also read that if a current value is below a threshold, that statistic has failed.

The value of the Uncorrectable Sector Count is 100, which is also its worst-recorded value, and the stat has a threshold of zero. Additionally, various other stats read that 100 is both their current and worst while not being marked "caution".

Why is Uncorrectable Sector Count being displayed as caution if various other stats with the same value and threshold aren't? How can a lower-than-threshold value occur with a zero threshold? Is this a sign of imminent drive failure or is the tool merely miscalibrated?

EDIT: Seagate's SeaTools utility has reported that SMART is OK, but it didn't say anything else.

  • According to Google's mass statistics, a drive with any uncorrectable sector counts (raw value > 0) are much more likely to fail in the near term HOWEVER this does not guarantee it will fail soon or ever will. As with any situation, make sure you have up to date backups. – qasdfdsaq Sep 22 '16 at 13:04

Why is Uncorrectable Sector Count being displayed as caution?

You need to look at the raw value (8) in this case. There have been 8 events.

The raw value of this attribute indicates the total number of uncorrectable errors when reading/writing a sector.

In this particular case, I would keep an eye on the value and if it continues to increase then replace the drive:

This is a critical parameter. Degradation of this parameter may indicate imminent drive failure. Urgent data backup and hardware replacement is recommended.

S.M.A.R.T. Attribute: Uncorrectable Sector Count

Attribute ID: 198 (0xC6)

Hard drives, supporting this attribute

Samsung, Seagate, IBM (Hitachi), Fujitsu (not all models), Maxtor, Western Digital (not all models)


Uncorrectable Sector Count S.M.A.R.T. parameter is a critical parameter and indicates the quantity of uncorrectable errors. The raw value of this attribute indicates the total number of uncorrectable errors when reading/writing a sector.


This is a critical parameter. Degradation of this parameter may indicate imminent drive failure. Urgent data backup and hardware replacement is recommended.

Source S.M.A.R.T. Attribute: Uncorrectable Sector Count

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  • Thank you for the info! I'm just about to begin a fresh backup. – Celarix Sep 22 '16 at 11:55

As concerns your first question, the three columns together tell you the status of an attribute.

Column "current" means the current value. Usually it is at 100 when everything is ok. Higher values often mean that the attribute has never been updated (implies 100).

The column "worst" tells you what worst value SMART has ever assigned to this attribute.

"threshold" is the absolute health threshold and indicates the value at/below which SMART consideres the attribute a failure. Most attributes that have a zero threshold are not critical. When they decrease, it just means that you drive gets older. Other attributes have thresholds greater than 0 and are often critical.

As concerns your second question, the uncorrectable sector count is an important attribute that very often indicates an imminent total failure. Watch this attribute very closely. If it increments too rapidly, it is better to look for a replacement drive. SMART is not always implemented honestly from what I've seen. 100% health with 8 uncorrectable sectors is such a case. Try to do a surface scan if you would like to save/check the drive, but before you do such an operation with high I/O load, make a backup.

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  • I did notice that the raw value of the stat reads 0x08 (only after I ask the question, naturally). Perhaps that's why caution is being displayed. – Celarix Sep 22 '16 at 11:50
  • Raw values are uninterpreted values from which the health is calculated. These are typically vendor-specific. For example some vendors store temperature in Celsius and others not. They also count sectors/errors/times there and you can't really tell how bad the status is without looking at the current value. – Martin Sugioarto Sep 22 '16 at 11:55
  • No. I do not understand it. RAW value is current value because until now 8 incidents happen. Correct? Threshold value is a bound. When RAW value > Threshold value a warning arises. So, the question remains: If RAW is current value, what is current value and what is worst value? How can current value be 100 when RAW value is 8? Current and RAW are not the same? Please write more. – Chameleon Jun 9 at 11:59
  • In this example 8 is the number of sectors affected. Uncorrectable means, well, they cannot be corrected by the logic of the drive. But there are several attributes that can be fixed and they will go back to zero. All thresholds are not just warnings they show clearly that a drive has failed. Raw is the same as current. Current is interpreted by UI and raw is what the attribute really contains. Sometimes the numerical attribute values are flipped (often temperature is shown as quality or real temperature). There is no real standard what a vendor stores as raw value. – Martin Sugioarto Jun 9 at 12:13

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