Hard Disk Monitoring

Yesterday I received a health warning on one of my drives. The log showed that there were 8 bad sectors. I ran a Quick Fix surface test and it found the bad block (only one bad block was found). During the repair it maxxed out at 48 Reallocated Sectors, and 149 Reported Uncorrectable Sectors. All 48 sectors were successfully repaired (relocated), and after the repair, both the Current Pending Sector Count and the Off-Line Uncorrectable Sector Count dropped from 8 back to 0. No change in the values of the Reallocated Sectors or the Reported Uncorrectable Sectors was noted in the log (I'm not sure if these would even drop after a repair). I reran the Quick Fix test - no errors reported. I also reran Repair test on the specific bad block - again no errors reported. I then ran a repair test on the entire drive, no errors reported. Finally, I ran a repair test on just the one block, and ran it 3000 times (yes, three thousand - it took about two hours), without a single error. Note that because the drive is Bitlockered (though temporarily disabled), HDS will not allow me to run a Read + WRITE + Read test (which I had wanted to try on the original bad block).

NOTE: I've attached a screenshot of the log history for this drive.

Despite the bad sectors supposedly being removed from further use, and the data from those sectors being reallocated (all the data was from a single file, and not a particularly important file at that), the health is still reported at 51%. Here's the history of the drives health:

• Before Sunday's automatic self-test: 100%
  Following the self-test (when 8 bad sectors were found): 87%
  Immediately following the repair: 48%
  About 15 minutes after the repair (which included retests and a reboot): 51%

By temporarily disabling various SMART values, I learned that most of this drop in health is due to the Reallocated Sectors Count, and 1% is due to the Reported Uncorrectable Errors (temporarily disabling both values restores the reported health to 100%). Since yesterday afternoon, the health has stayed at 51% despite multiple error-free read tests and reboots of the system.

Normally when I run a repair on a drive that's reported bad sectors (it's normally been a different drive on this machine), the health resumes most of it's value within a day or two of the repair. But in those cases, the health has dropped only a couple of percentage points, and the errors are almost always Current Pending Sector Counts that increments from 1 to 7 points, but then drops back down to 0 following a repair. However, in looking at the logs, I think this is the first time I've seen Reallocated Sector or Reported Uncorrectable Errors on any of my drives, so I am less familiar with how the drive health should behave over time. So I'm wondering if the drive health will revert back to 100% (or near that) on it's own in a few days. If so, is there also a way to "force" it back? I don't mean adjusting the offset, but rather can I have the system re-evaluate the drive by doing something other than what I have tried so far?

If the drive health will stay at 51%, I may at least temporarily adjust the offset. However I want to know how at risk this drive is based upon this one error (which is clearly only one block at the moment, and after the repair I am not getting any read errors despite thousands of read tests on the original bad block). If you think that a write test is the only way to know for sure, is there a quick work-around to Bitlocker preventing such a test?

To be short:

Please check the Support -> Frequently Asked Questions -> How to repair hard disk drive? How to eliminate displayed hard disk problems?
https://www.hdsentinel.com/faq_repair_h ... _drive.php
page which describes the situation: that _after_ the disk drive repaired (all problems stabilized) then we may need to adjust the error counters, exactly to acknowledge the issues and clear them - and be notified about possible new problems only (if there will be). This also restores the hard disk Health % too.

Please scroll below for the step-by-step details in your case now.


But first maybe you are interested in the details:

I can confirm that Hard Disk Sentinel immediately detects and reports the new status of the disk drive.

Generally the Quick Fix, Disk Repair (and possible other tests, even the destructive tests) designed to stabilize, correct the status of the drive: reveal and correct possible weak/damaged sectors which still used by the disk drive and can cause data corruption / data loss.

These sectors (incorrectly) identified/reported as "bad sectors" by chkdsk (which does not fix them by any ways just makes things worse), causing false assumptions.
This described with more details at:
https://www.hdsentinel.com/hard_disk_ca ... ectors.php


After the Quick Fix / Disk Repair or the tests (so after this correction) the result can be:

- the sectors (if verified and confirmed that can be re-used) restored to normal state by the hard disk drive. Then they are no longer reported as pending sector or weak sector: the text description on the Overview page does not show them and the Health % of the hard disk drive automatically increases back. Probably you see similar situation previously.

OR

- the sectors (if they are really damaged and should be no longer used) reallocated by the hard disk drive: the hard disk tries to move all data to a spare sector (which not yet used, as it is on a dedicated spare area) and then re-directs all further reads/writes (targeting the original bad sector) to this spare sector.


In both cases, if you attempt to re-read (or write) (so re-test) the affected sector, you'll receive no errors: the sector may be repaired (so works correctly) OR (in the second case) the drive automatically reads/writes the spare sector instead. So ideally we can say the drive is repaired, perfect and working - with no issues.

The hard disk drive automatically counts and provides all such bad sectors (and other issues) ever happened in its lifetime by the S.M.A.R.T. attributes (of course, as this way we always know the actual status, verify possible degradations and can estimate the used spare size). No, I'm afraid usually these values always kept/recorded by the drive, never automatically restored to zero.

As reallocations always risky (can cause data corruption, data loss or "just" system hangs/downtime etc) it is important to KNOW this situation. Some small amount of bad sectors (really) acceptable as described on the Support -> Frequently Asked Questions -> I have bad sectors....
https://www.hdsentinel.com/faq.php#health

But with relatively high number of reallocated sectors (eg. 100's or more) we can expect even more. Depending on the value of the stored data and possible downtime plus considering other factors, (eg. the power on time of the hard disk drive) we can decide if we continue using that hard disk drive - or plan replacement, maybe in the time displayed as estimated remaining lifetime. Some users/companies replace immediately on 90% hard disk Health (or even sooner) and in really critical situations I'd do that too.

This is why automatically the Health % is not restored, but exactly as described on the first link, after you confirmed (with the tests) that the disk drive is stable, you can select to "ignore" these problems (as they already fixed) and want to be informed about possible new problems only - if they'll ever happen.

This is exactly the purpose of the Offsets on the S.M.A.R.T. page: by using them, you can clear the error counters and restore the Health % too.

You can temporary disable the attributes too - exactly to "hide" the problems, as then Hard Disk Sentinel will completely ignore them and the values they'd report. As a result, you can always see a high Health % value - but then you'll never see possible changes / degradations (new errors), so it is better to use the Offset value, exactly because now there is high chance that you may see degradation in the future. Probably not tomorrow or in some weeks - but maybe later, likely in a sector near the original bad one.


To clear the error counters now, please open the S.M.A.R.T. page of the hard disk in Hard Disk Sentinel.

1) Locate the attribute 5 Reallocated Sectors Count
In the Offset column between the + and - symbol, click on the number and acknowledge the notification.
Specify
-48
in the small box (the amount of errors reported just with negative sign before it)

2) Repeat the above for attribute 187 Reported Uncorrectable Sectors
and specify
-149
there too.

Soon the problems should vanish from the text description and the health should increase back as well. The Health % graph on the bottom will still show the low value today (as it shows the daily lowest health) but from tomorrow it should increase back.

Then, as the problems are already fixed, they will be no longer counted/reported by Hard Disk Sentinel, just possible future problem(s) will be reported, if there will be any.


Ps. no need to use write (destructive) test now. The quick-workaround are the Quick Fix and Disk Repair tests - as they designed exactly to perform a read scan and specifically repair the sector(s) without performing a complete write test - which not always possible, eg. by Bitlocker.


Sorry if was too long or boring, just wanted to explain. However if you search on the forum, you may find similar topics too