Health recovered by itself from 55% to 100% ???

[NBrooks]

My D Disk health suddenly dropped to 55% about 10 days ago. After checking the documentation, it seems that bad sectors had been found and permanently marked as swapped.

Today it has recovered to 100%. This seems inconsistent with the docs, the life expectancy was about 100 days, and I'd resigned myself to sourcing a new disk. It is now saying over a year life expectancy.

I don't understand what has happened. I rely on HD Sentinel to warn me of impending problems, but this has shaken my confidence significantly.

Attached are shots of the graph and the data. Note that no offsets have been applied. Unfortunately, I don't remember if any of the data was different when it was reporting 55%.

What would have reset the data/health. I understood that once sectors were marked as bad, that was the end of them ?

Thanks
Nigel

HDS 1.jpg (172.12 KiB) Viewed 4377 times

HDS 2.jpg (227.94 KiB) Viewed 4377 times

[hdsentinel]

Not sure what exactly detected/reported previously, would be nice to know if _surely_ bad sectors detected.

Yes, exactly as you wrote, the bad sectors should remain bad and their count should not decrease.

I'd suggest to please check the Log page. That page designed to show possible changes with the important attributes (for example bad sectors) so it may show if there were bad sectors present or not.

Also if you open the S.M.A.R.T. page and select any attribute, you can check how that changed with time. On the screenshot you sent, the Reallocated sectors count attribute shows a constant 0, so seems no bad sectors ever reported on that attribute. You may check other attributes too for possible changes (eg. Current pending sector count, Off-line uncorrectable sector count and so).

Is it possible that you may adjusted the Health calculation method at Configuration -> Advanced options page?
That option affects how the health value is calculated, so by changing the method, you can get different health results for the disk drive, it is normal and expected.

I'd suggest to please use Report menu -> Send test report to developer option, as it would be nice to check the status of the disk drive as it may give further ideas/thoughts.

[NBrooks]

Thanks, nope, I didn't adjust/change any settings, the screen shorts are attached, both Current pending sector count and Off-line uncorrectable sector count had 'blips', what does this mean ?

I've also done the "Send test report "

Cheers
Nigel

I did this reply message earlier, but it did not appear, so repeating !

[hdsentinel]

As you can see, there were weak sectors detected, displayed previously. Those weak sectors (reflected by the Current pending sector count attribute) caused the lower health value, exactly as expected.

As described on Support -> Frequently Asked Questions -> What is a weak sector? How to repair weak sectors?
( https://www.hdsentinel.com/hard_disk_ca ... ectors.php )
these weak sectors can cause troubles but in many times these related to the operating environment: cables, connections (or even a reset/sudden power loss) can create such weak sectors.
Because of their nature, these can be usually completely and correctly fixed, repaired (the above link gives details, for example Disk menu -> Surface test -> Disk Repair). In a lucky situation, sometimes these weak sectors could be automatically repaired after some time and normal usage too.

Because of these, yes, the weak sectors repaired - and the health restored to 100% - as expected in an ideal situation.

Some disk drives count and report bad and weak sectors together. We may think these are different - but they related to same sectors (and same issue): as you can see those two attributes increased/decreased together (so they refer to same issue, same sectors). This is why that count also reduced back to zero when the weak sectors repaired and the status is now fine.

I recommend to check the link:
https://www.hdsentinel.com/hard_disk_ca ... ectors.php
for details about how to generally avoid such sectors (eg. check cables, connections and so) exactly to avoid similar situation in the future.