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My main HDD is a 2TB Seagate ST2000DM001. Recently I got weird issues which turned out to be related to bad sectors (the HDD disappearing all of a sudden from the system, a BSOD with no other likely cause) : a red warning in HD Sentinel indicates that there are more than 1300 weak / bad sectors. I stopped using it, then successfully cloned it to another healthy 2TB HDD using ddrescue. There was indeed an unreadable area around the 3GB mark, leaving about 600KB of error size. The rest of the HDD was flawlessly recovered, with no slowdown, so it would appear that there is just one spot that is problematic.

I'm currently attempting to repair it using HDD Regenerator – a quite controversial piece of software from what I could gather, but so far it seems to be working, albeit very slowly (180 sectors considered "recovered" in 30min.). In the past I successfully regenerated a bad sector on a 2TB WD HDD, which caused CHKDSK to fail with a "not enough space" error, using that software followed by a defragmentation (WD's Data Lifeguard Diagnostic only reported a failure and could fix nothing) ; the SMART parameters were back to normal after that, CHKDSK could finish its process, and that HDD is still in use several years later.

Now, in case that defective area can not be repaired, would it be safe to continue using that HDD for non-critical / temporary data storage ? Or should I consider that it is no longer safe for the integrity of any data whatsoever ? Is it harmless for the the drive's heads unless they come directly over a severely defective area, or can they get damaged even if working in the vicinity, without attempting to directly read from or write to that area ?

GabrielB
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  • Just as a Peanut Gallery comment, I wouldn't trust it. I loathe discarding old hardware that may be of use but, unlike your experience, I have never had a failing drive last very long. Considering another drive of similar size is likely less than $100, my guess is you could buy at least one more while waiting for the failing drive to cause you completely unnecessary headaches. – Anaksunaman Sep 19 '17 at 09:31
  • I see that I got a “–1” vote for that question... Is there a particular reason for that ? O_o Can someone downvote any question / answer / comment here with no explanation as to why they did it ? Well, I've got enough on my plate right now to focus on my “reputation score” on a website, as good and helpful as this one can be, but still, it's quite puzzling... (I reckon that I'm way too easily puzzled – that should grant me an “easily puzzled” privilege or sumthin’ like that. * SIGH *) – GabrielB Sep 20 '17 at 14:43
  • No explanations are required for up or down votes (though you do need 125 rep for downvotes IIRC). Someone likely felt it failed some criteria for questions - - https://superuser.com/help/how-to-ask – Anaksunaman Sep 20 '17 at 14:56

4 Answers4

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Been using WD black 1TB with 2 bad block isolated in separated partition almost 2 years, and everything is just fine. Just make sure to separate a little more than just bad block's size. 1GB before and after will suffice.

But no one can guarantee you anything. May work just fine, may die tomorrow.

Use it for non-important data only.

Bachi
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    Yeah, with the experience I've had so far, I wouldn't worry too much about 2 bad sectors (I would of course check it closely, but even a brand new HDD has to be checked regularly). My laptop's HDD had 3 when I bought it (used) in 2012, it hasn't evolved since. But here the count is in the hundreds, so it's definitely a serious issue. I think I'll create a partition begining at the 5GB mark, to be on the safe side, and see how it behaves that way. – GabrielB Sep 19 '17 at 23:25
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Just to share my experience regarding HDD Regenerator...

Before using it, I checked Hard Drive Sentinel which reported 1312 “weak sectors” (in the SMART tab they appeared at the “Current pending sectors count”).

enter image description here

I then ran HDD Regenerator, which after about 105min claimed to have “recovered” all the 1312 sectors, all contiguous and located around the 3072MB mark.

enter image description here

Then, it proceeded at a much higher rate (although still slow – it went from about 1 sector / second to about 5MB / second). I stopped it, and checked Hard Drive Sentinel again : the red warning was still there, the health status was still estimated at 9%, and it appeared that the bad sectors had merely been remapped / reallocated (now in the SMART tab they appear at the “Reallocated sectors count”). Plus there are many more data transfer errors (“Reported uncorrectable errors” went from 1333 to 3958 – although I'm not sure what it means exactly).

enter image description here

So, it turns out that HDD Regenerator did not in fact regenerate anything, it just forced the reallocation of those sectors, just like attempting to write on them with any other tool would have done. Bummer.

A nice thing though is that this software provides a list of the affected sectors, which can be useful. If they are all located in the same area (as is the case here), one can take the risk of partitioning around that bad area so as to continue using the HDD for really non-critical data, like storing movies which are backed-up elsewhere to watch them through a set-top box or whatnot (that kind of usage has the advantage of not impacting a working computer in case of a severe failure, which may freeze the system, cause a BSOD, resulting in some loss of data or other possibly serious inconveniences) ; if they're scattered all around the surface with no particular pattern, then the HDD is really toast and should be discarded remorselessly.

HDD Regenerator - list of the bad sectors

GabrielB
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  • I concur, there's no way a software could "regenerate" anything that is related to hardware defects. However, there are two ways to make a "pending sector" reallocated: writing new data on it, or succeeding reading the data it contains. Since HDD Regenerator claims the existing data won't be lost, I guess that it is attempting reading the pending sectors until it succeeds (there's probably a time limit, though), and once done either the controller reallocates the sector on his own because of too meany read errors on it, or HDD Regenerator has a way to force the reallocation. – PierU Dec 08 '22 at 09:55
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The short answer is that it's not recommended, especially if you've had it for a long time (if you bought it recently, backup your data then replace it under your warranty).

The long answer is that the drive's firmware intentionally has some extra space dedicated to handling bad sectors. The drive does not expose this extra space externally and you cannot intentionally use it. It has one purpose - when the drive encounters physical defects it automatically consumes one of those extra sectors and moves the logical sector to use it. The old, bad, physical sector is never used again. All of this is completely transparent to the user and the OS, although you can check how many such sectors have been used through a S.M.A.R.T monitoring program (you can use a free small utility called CrystalDiskInfo for that, it appears as "Reallocated Sector Count"). As long as there are still unused extra blocks, chkdsk /r will not report any physical defects.

When chkdsk does report physical defects it means that the drive has run out of extra space and can no longer fix any errors. At this point things will degrade relatively quickly. You will encounter more and more bad blocks over time, and any data that happened to be stored there will be lost. You should backup your data and replace the drive as soon as possible.

Hard drives have a finite lifespan, usually around 5 to 7 years (depending on usage), so this is pretty much expected.

Dan
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    *"when the drive encounters physical defects it automatically consumes one of those extra sectors and moves the logical sector to use it"*: that's not completely true. The controller won't reallocate a sector on his own if it is unable to read the data contained in the sector. – PierU Dec 08 '22 at 10:17
  • fair enough, but it still raises a red flag and if the hard drive is relatively old any bad sectors should be a sign that the drive needs replacing. – Dan Dec 08 '22 at 10:19
  • "When chkdsk does report physical defects it means that the drive has run out of extra space and can no longer fix any errors." No, they can be pending sectors. – Joep van Steen Jan 11 '23 at 02:27
  • Checking this quite late. I wouldn't agree that HDDs have a finite lifespan; even under regular use, some can easily last 10 years, even with a light use, some can fail within months. Then, what appears as bad sectors can be related to a head failure rather than a weakened magnetic layer on the platters, in which case they start accumulating very quickly, with a typical “alternating stripes” pattern, as I experienced in q/1244575 — and as was probably the case with the unit mentioned here (still have it but it became very unstable very quickly). – GabrielB May 22 '23 at 03:51
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Just to add upon the other answers, I would monitor the SMART report of this disk from time to time. If the "Reallocated sector count" remains stable, then the problem was likely limited to a specific area of the disk for some reason (the heads may be scratched the platters because of a shock, or whatever...), and you may continue using the disk. If the "Reallocated sector count" keeps increasing then the disk is likely failing, and soon or later you will have problems again.

PierU
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  • PierU, when a sector is unreadable it increases the "pending sectors" counter. Only a write command to the pending sector can trigger a replacement of the sector, thereby increasing the "reallocated sector count". Therefore your whole disk can become unreadable without an increase of "reallocated sector count". That's why I downvoted your answer. – r2d3 Jan 10 '23 at 23:37
  • @r2d3 you could also say exactly the same thing for the "pending sector" count: it's only when trying to read them that they can be detected, and depending on the usage of the disk it could become unreadable without an increase of the pending sector count. – PierU Jan 11 '23 at 07:20
  • Yes, that is correct. – r2d3 Jan 11 '23 at 16:57
  • @PierU That's akin to the Schrödinger's cat thought experiment! That particular sector could be construed as both dead-and-alive until its status is assessed and reevaluated as “murder-death-killed” as they say in the movie Demolition Man. – GabrielB May 22 '23 at 04:08