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S.M.A.R.T warns of bad sectors, but the disk is healthy!

Last response: in Storage
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July 1, 2011 4:03:40 PM

OK, here's the problem... the S.M.A.R.T diagnostic shows 35 bad sectors; well, actually 35 reallocated sectors, n ot bad per se AFAIK. So I dutifully ran chkdsk and it showed no bad sectors. So I pulled out my new copy of HD Regenerator. No bad sectors. So I dusted off my old copy of SpinRite . Guess what? No bad sectors.

Windows 7 is jumping up and down about imminent, catastrophic failure wrt these 35 reallocations on a drive with over 979 million sectors.

So I contacted my brother who works for a professional data recovery firm who specialize in sensitive data. He sent me some of their tools, which I ran.

Anyone want to guess what happened?

Yup. No bad sectors. Disk is perfectly healthy.

Bro looked at the logs from their tools and told me the disk was 100% fine and assured me this was a SMART false positive which can be ignored; just keep tabs on any increase in errors.

I trust him, but should I tell Win7 to "eff off" when it comes to the warnings and click the "never speak of this again" button on the warning window?

And, yes, the important data is backed up; I just want to know if SMART is being err.. stupid.
a c 415 G Storage
July 1, 2011 6:56:21 PM

Reallocated sectors are not that big of a deal, unless you find you're getting more and more of them over time. What's happened is that the drive has found some sectors with problems and has moved the data to spare sectors. That all happens inside the drive - at the level of the operating system (chkdsk, for example) all of the sectors appear to be just fine.

What program exactly is giving you the error messages? Windows 7 itself doesn't check the SMART data - it sounds like you have some sort of monitoring software that's doing this. You should be able to configure that software so that it doesn't report reallocated sectors.
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July 1, 2011 8:20:28 PM

It's Windows Disk Diagnostic that's giving the warning, which does read the S.M.A.R.T. data. I think it's a standard part of Win7 now.

I could only access the S.M.A.R.T. report through ActiveS.M.A.R.T., which has no options to tell it to ignore reallocated sectors. Plus it has a really low tolerance for them - the "limit" is 36 (I've got 35). Checking the logs, it looks like all of them appeared at once when the drive hit 63 degrees (yes - really hot here, and the AC packed up that day!) Like I said, surface scans produced no hits, and there was no head crash, so I assume it's a "soft" sector error. I ran a full defrag and free space wipe to see if that got rid of the error, but no luck; S.M.A.R.T. thinks there are bad sectors but nothing else does.

I just ran SeaTools (it's a Seagate drive) and, once again, no bad sectors. WHich means that even though it's in warranty they won't replace the drive, since their diagnostics won't reveal any issues. Sucks. :( 
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a c 104 G Storage
July 1, 2011 8:27:47 PM

Hi there,

Sminlal's question about what S.M.A.R.T applet you are using and what the alerts are, is very pertinent.

We have all seen alerts occur when one parameter drops a point, the spin up time changes (up or down), the temp changes (up or down) etc., so could the alert be related to another parameter? Review them all. In the S.M.A.R.T. health reports sometimes it gives you a number change, say 180 - 178, where the alert level is much lower like 35.

Am impressed that you have good old SpinRite, and you did take the time to check out the whole disk surface!
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a c 415 G Storage
July 1, 2011 9:39:12 PM

This is interesting - I did manage to find a reference to the "Windows Disk Diagnostic Module". I strongly suspect the messages you're seeing really are triggered by going over some set threshold, since I have a reallocated sector on one of my drives and I've never seen any hint of a message about it.

It looks like it's possible to turn off the module by going to the following Registry Key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\DiskDiagnostics\FallbackPolicy

...and changing the "EnabledScenarioExecutionLevel" value from "2" (enabled) to "1" (disabled).
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July 2, 2011 11:28:22 AM

John_VanKirk said:

We have all seen alerts occur when one parameter drops a point, the spin up time changes (up or down), the temp changes (up or down) etc., so could the alert be related to another parameter? Review them all. In the S.M.A.R.T. health reports sometimes it gives you a number change, say 180 - 178, where the alert level is much lower like 35.


I looked over pretty much everything and it was all fine (ActiveSMART gives "OKs" to everything so it's almost idiot-proof). It looks like the threshold value for reallocations is 36 for some reason, and I have 35. On a 500GB drive.

Methinks it's a wee bit sensitive.
John_VanKirk said:
Am impressed that you have good old SpinRite, and you did take the time to check out the whole disk surface!

Ah, it only took 90 minutes. chkdsk was the one that took 2 hours! :D 
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a c 104 G Storage
July 2, 2011 3:26:55 PM

Making Progress!

I have ActiveSmart on an older XP computer I'll try to hook up and look at the Sector Reallocation parameters.
I used to get alerts frequently with ActiveSmart as it changed different S.M.A.R.T parameters even small amounts, like the temperature going up, or down 2 degrees.

Take a look at the starting value of the Sector Reallocation on ActiveSmart. If it started at 100, or 200 then 35 would be very significant.
Those starting values, and even if a parameter is listed, depends on the drive maker and how old the drive is.

I am using HD Tune Pro on this computer, which shows the starting Sector Reallocation Count at 200, with a threshold of 140
Another option for thoroughness, would be to download the free version of HD Tune, and check the Health values with it.
You can always uninstall it.

Let us know what you find.
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