Me thanks too, I'm glad if I could help
I hope it was not boring or too technical, just wanted to explain things.
Many times users ask "why Hard Disk Sentinel does not automatically make the offset and show that the hard disk is perfect?"
Exactly because it does not want to "hide" problems and showing that things are good - until we understand the background, how things work and how then it is even more important to monitor and verify possible changes / new problems.
> That aside, I have done the SMART reset that you've provided and all is well.
> I am guessing this is only used if and when you have done all the tests I have mentioned previously?
Generally, it is possible to perform the reset of the S.M.A.R.T. any time - but yes, exactly as you wrote, it is best to do AFTER performing the tests, when you confirmed that the status is really stable, there are no new problems.
> Since no files scanned were in the bad sectors and all reports are green,
> it is safe to say the status would be 100% again I think until new errors are reported.
Yes, as the tests confirmed that all problems already fixed (by reallocation, so all previous bad sectors already replaced from the spare area) then now it is safe to say that it is 100% perfect and usable - exactly as you wrote: until new errors are reported.
> When you run chkdsk and it finds bad sectors several things happen
> there is an attempt to move any data to a good sector and the bad sector is marked in the
> HDD firmware as a user found bad sector so it will not be used again.
This is absolutely FALSE.
> The bad sectors cannot be repaired so they are mapped out and never used again.
> You don't need to reformat to deal with them.
This is absolutely FALSE.
> The data that was in the bad sectors may not have been recovered so some files may be corrupt.
Yes, this is TRUE.
When chkdsk finds an unreadable sector (which is considered "bad" in the chkdsk terminology), then yes, it marks that sector in the CURRENT FILE SYSTEM (partition) only as "bad" to prevent further access of that sector.
There is NO attempt to move the data anywhere (the current file system / partition has no spare space for that).
There is NO attempt to force the hard disk to repair the sector "internally" in the hard disk firmware, chkdsk performs fixes at the level of the current partition.
So what will happen if you ever remove the partition, for example making new partition(s) to perform a clean re-install?
That sector will be happily re-used and can cause data corruption, data loss.
So then the disk problem remains, chkdsk happily show that there is XX bad sectors on the current partition.
Yes, there is a better way which really forces the hard disk to move data to spare area, replace the sector from the spare area and then the original area will be no longer used. This is the reallocation performed by the hard disk and this may happen any time (but not with chkdsk) if required.
Just some methods, for example the Disk menu -> Surface test -> Reinitialise disk surface test in Hard Disk Sentinel are intensive enough to let the hard disk find out easier that the sector is really damaged and should be replaced from the spare area - if required.
The problem is that chkdsk only "see" and "fixes" sectors which are not really bad. The "real" bad sectors (which already re-allocated and replaced by the hard disk) never found by chkdsk.
The sectors chkdsk finds are the "weak" sectors, which are really damaged somehow and should not be used to store data in their current form, until the hard disk really verifies their status - and reallocate (if required) or repair the sector.
The page
http://www.hdsentinel.com/hard_disk_cas ... ectors.php
exactly describes this situation:
1) when weak sectors reported by Hard Disk Sentinel, chkdsk shows "bad" sectors in the volume. We may assume they're fixed, but no, just chkdsk marked the volume to never use those bad sectors in this partition.
As you can see, these reduce the usable capacity (xx KB in bad sectors) - as the current partition has no reserved space for this purpose.
2) when we fix the problem with Hard Disk Sentinel (which increased the health back to 100%, without using the offsets or any S.M.A.R.T. manipulation, just by the Reinitialise disk surface test), and perform the re-format, then chkdsk finds and reports no problems.
And the "best": when you image/clone the original partition (where previously chkdsk reported bad sectors) to a new (tested and surely perfect) hard disk, this will clone the partition meta-data, including the marker of the bad sectors previously saved by chkdsk.
So then on the new hard disk, you'll have a partition with the same number of "bad sectors" (reported by chkdsk) - even if that hard disk is 100% healthy and there are no problems at all.
> But as I said, run chkdsk again in a week or so to see if there are more found
> it is symptomatic of a bad drive if they continue to be found.
You may run chkdsk any time to verify, reveal and fix possible problems with FILE SYSTEM (the current partition).
But if you want to diagnose, verify, reveal and fix possible problems with the hard disk, then chkdsk is NOT a good solution.
> <---Nice response I found while seeing if I could 'recover/fix' bad sectors...
Nice - but leads to wrong direction.
> So all in all, what would you suggest I do with this hdd now that it reports 121 bad sectors?
> Since it is sort of still viably usable still but would need more monitoring and/or replacing soon,
> should I just put it aside and use a new hdd altogether?
As the hard disk status is stable now, it can be used.
If this would be a young drive, personally I'd use only with constant monitoring and considering to have spare space as I'd perform immediate backup on any (even minor) new problem, degradation.
However, considering that it's power on time is 1901 days, it may be fine for storing old data, backups etc... which are not used daily.
> Is there a limit on how many bad sectors a hdd should have before replacement or
> rather how many it can take it can't replace any more bad sectors with good sectors?
There are such limits - but the problem is different.
10-20 (or even 121) bad sectors can be fine if their number does not increase.
The problem is that higher number of bad sectors may result higher risk of even more bad sectors to be reported in the future (due to the areal density, neighbour sectors can also fail). And usually not only 1-2 new bad sectors detected, their number can easily jump - and in most cases, with 1000's bad sectors (even if there may be room in the spare area) the hard disk usually become unusable.
Usually really high number of bad sectors required to reach the error-level threshold set by the manufacturer.
And usually hard disks dies before that (or at least partial / complete data loss occur).
Generally, this is why long time ago people started to think that S.M.A.R.T. data is not able to predict failures - but just it was incorrectly used by checking the error-thresholds only (and still incorrectly used in other tools and system BIOS).
The page
www.hdsentinel.com/smart shows the problems with this approach and how Hard Disk Sentinel does differenly by reporting the real error counters.