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can i unflag the bad sectors on my harddrive?

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hi, i've recently repaired a hard using spinrite, and it is now showing no bad sectors/clusters when i scan it. the problem is that chkdisc had previously flagged the bad clusters/sectors, and now even though they are repaired, the flags that chkdisc created are still there and so windows won't use the repaired space. is there any way to delete them without formating my drive? as i have data on there and can't afford a new harddrive at the moment to back it up.

i look forward to your reply


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The safest way is to run the command CHKDSK /F

"Another way to do it is to edit the Registry directly and remove the AUTOCHK command. To do this, navigate to HKEY_LOCAL_MACHINESYSTEMCurrentControlSetControlSession Manager in the Registry and look for a REG_MULTI_SZ value with the name BootExecute. Set the value of BootExecute to a null value. This will prevent AUTOCHK from running on next reboot."

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thanks for your response,

does this change what chkdsc has already done to the harddrive? it has marked bad clusters on the hard drive (lots of them) , and it will not change them back to ok, even though spinrite and other programs are saying the drive is fine. if i save anything onto the area marked with bad sectors it becomes incedibly fragmented. my computer marked these bad clusters months and months ago, windows has been reinstalled since then, so the bad cluster flags must be physically on the harddrive not in the registry, in the index or something, and it's this i want to change. is there anyway to edit the place where these bad cluster flags are indexed on the disk?

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hi 'Matts PC Help',

the problem isn't with chkdsc running. the problem is with chkdsc not retesting clusters that it has previously marked as bad, once it's marked them that's it! it will just avoid them on future checks. microsoft have noticed this problem with XP and have improved chkdsc on vista and windows 7, letting u tell chkdsc to retest the clusters and mark them as good if they pass.

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Hello 666philb,

The easiest way I know of to unflag bad clusters in XP is at the bottom of this page:


But, unless you are familiar with linux, I wouldn't exactly call it an 'easy' process. And also, if you don't get the process exactly right, you could possibly end up with a computer that will not boot up afterwards. So, personally, I would not attempt this process unless I had already backed up all my data.

However, I may have just had a brainwave. (Or, possibly, it could be a brainFADE, lol.)

We know that, in Vista, Microsoft have improved chkdsk so that it will now retest bad sectors and unflag them if they test as good. This is done using the /B command. (Which, unforunately, is not available in the Windows XP chkdsk version.)

I am wondering what would happen if you downloaded and burned a Vista Recovery Disc:


then used it to boot your computer and choose the 'Recovery Console' option. Then, at the command prompt, you typed chkdsk c: /B

You would then be using the Vista version of chkdsk to check your C: drive.

I have no idea whether this would work or not, and I do not recommend that you try it without further research. If it does work, though, it's a heck of a lot simpler that using linux and ntfsclone.

Best of luck.


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thank you for replying

in response to both of you, i used spinrite on level 4 but change it to 5 when the program had just started, i believe this is its most intense scan and repair.

and yes i had seen the linux solution, and thought yes i'll do that, then booted up linux for my first ever go and realised it wasn't going to be that easy :D but your using the vista recovery disc is a wonderful idea, i've just burnt a cd and will try it now..... fingers crossed

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SUCCESS!!!!!! :D

using the vista recovery disc and running chkdsc d: /b for my d drive has unflagged nearly all the previously marked bad sectors, there were over 2gigabytes of them! they were spread in a kind of pattern around the inside of the drive and a thin band around the edge, badcluster - empty space - badcluster - empty space and so on..... and every time a file got saved to this area it got incredibly fragmented as you could imagine. i still don't know what caused this but will be definately keeping an eye on it.

thankyou 'marktreg'

for a brilliant and simple idea.

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That's great news. I'm really pleased that it actually worked. :D

I honestly had no idea whether it would work or not. I just got to thinking that the actual file systems in XP and Vista were the same (NTFS). It is only the actual files that make up the operating system that are different. And, if you research chkdsk, it only ever seems to mention the NTFS file system, not the operating system. So, it occurred to me that the actual operating system might not matter as long as it was an NTFS file system. That was how I came up with the idea in the first place. But, as I said, I really had no idea whether it would actually work or not. I suspected that there might be some kind of complicated problem that I might have overlooked. But apparently not. Nice one. :D

Happy computing phil.

All the best,


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i've read that article on spinrite and will probably take your advice, i think i was lucky as the badblocks that were marked on the disc, weren't really bad (there is one badblock 8kb) so spinrite never got stuck. i've enclosed a picture which shows what happened to my drive, unfortunately i took it after the repair but you can see the bad block paterning around the edge and all of the white area in the middle was checkered in a similar pattern.

any ideas why this happened?



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