MFT corrupt (Windows 7 32-bit)


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jsampson45
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Today my scheduled image backup failed with "MFT corrupt - Error code = 6. Please run 'chkdsk C: /r'". This happened a few days ago so I ran chkdsk from the rescue disk. This took a few hours, but after that a backup occurred successfully. Now the error has recurred. I had been using the computer for some days previously with Macrium reporting the "MFT corrupt" error recurring each time there was a backup scheduled. It seems that having a "corrupt MFT" does not affect use of the computer, except to prevent Macrium doing backups. Is the MFT really corrupt? If so, what causes the corruption?

jphughan
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My guess is that your disk may be about to die, but MFT corruption is most certainly not a problem that only gets in Reflect's way, even if it's something that you only notice as a result of Reflect.  MFT stands for "Master File Table", and to oversimplify it, it's the directory that the NTFS file system maintains to keep track of what files exist on the disk and where they exist on the disk.  As you can probably imagine, that's not an entity where you want to have corruption.  It's entirely possible that you're just not noticing anywhere else because your daily usage doesn't have you trying to access files whose MFT entries have been corrupted, whereas Reflect is trying to capture the entire disk.  NTFS does also maintain a "Backup MFT" that may be ok, fyi, but I don't know if Reflect throws that error as a warning when the primary MFT is corrupt even if it can work with an intact Backup MFT or if seeing that error means both are corrupted.

In any event, if you ran chkdsk /r previously and this error is back a few days later, I would buy a replacement hard drive asap.​​
Nick
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jsampson45 - 30 October 2017 2:47 PM
Today my scheduled image backup failed with "MFT corrupt - Error code = 6. Please run 'chkdsk C: /r'". This happened a few days ago so I ran chkdsk from the rescue disk. This took a few hours, but after that a backup occurred successfully. Now the error has recurred. I had been using the computer for some days previously with Macrium reporting the "MFT corrupt" error recurring each time there was a backup scheduled. It seems that having a "corrupt MFT" does not affect use of the computer, except to prevent Macrium doing backups. Is the MFT really corrupt? If so, what causes the corruption?

Hi

The error indicates that at least one used file cluster is marked as unused in the NTFS bitmap. The bitmap is a record of all used and free clusters in the file system. When a file needs to allocate a new cluster it uses one of the available clusters in the bitmap and then marks it as 'in use'. So, in this error situation, there is a danger of losing data due to a cluster being used by more than one file.

This should be very rare and, to my knowledge, can only occur after power failure during a file system write or, of course, a failing disk . 


Kind Regards

Nick - Macrium Support

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Edited 30 October 2017 3:04 PM by Nick
Seekforever
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I agree with jphughan, there is very likely a problem with your disk since it was corrected and now the same problem has reoccurred and it needs replacing.
You could download the disk manufacturer's disk diagnostic program and see if it provides any more insight into the disk status.​

Edited 30 October 2017 6:36 PM by Seekforever
CharlesOrr
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Hi 
My drive  C is a  Samsung 970 Pro Series 512GB M.2 2280 M-Key PCIe SSD Drive, single-sided (MZ-V7P512BW).
It is 10 months old  and I am now seeing   MFT corrupt Error 6 fairly often after trying to image it.  Running chkdsk  fixes the problem.
However, given the nature of the drive, does this really mean it is about to fail?
Can you shed any light on this matter please.?

I have a  identical replacement drive that I regularly clone  the current drive C image to in case the worst happens.
Also can you reassure me that if the worst does happen, all I have to do is install my cloned drive and all will be well again.
I have up to date recovery media and of course I image Drive C every night so have this  option for recovery as well.

Many thanks

Charles


Nick
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CharlesOrr - 4 June 2020 10:05 AM
Hi 
My drive  C is a  Samsung 970 Pro Series 512GB M.2 2280 M-Key PCIe SSD Drive, single-sided (MZ-V7P512BW).
It is 10 months old  and I am now seeing   MFT corrupt Error 6 fairly often after trying to image it.  Running chkdsk  fixes the problem.
However, given the nature of the drive, does this really mean it is about to fail?
Can you shed any light on this matter please.?

I have a  identical replacement drive that I regularly clone  the current drive C image to in case the worst happens.
Also can you reassure me that if the worst does happen, all I have to do is install my cloned drive and all will be well again.
I have up to date recovery media and of course I image Drive C every night so have this  option for recovery as well.

Many thanks

Charles


Hi Charles

Thanks for posting.

NTFS maintains of map of file system clusters in use by files as well as clusters not used. This is called the Volume Bitmap or $BITMAP. The accuracy of this map is crucial to the file system to ensure that clusters are assigned uniquely and data isn't overwritten when new files are created. Macrium Reflect uses the $BITMAP file to backup all used clusters when creating an image. The File System check at the beginning makes sure that the clusters in all files are marked as used in the $BITMAP file.

Error code 6 indicates that the scan found at least one file where a used data cluster was marked as free by the $BITMAP file. This would lead to data loss when creating an image and is potentially dangerous for the file system because the orphaned clusters could be overwritten by a normal file operation at some time in the future. 

This situation is easily remedied by running chkdsk. This error should be a very rare occurrence as NTFS is exceptionally reliable at tracking data writes.

I wouldn't think that this error is indicative of a failing disk as disk errors are flagged and clusters excluded from the file system completely. If the system has experienced unexpected shutdowns or BSoDs then it's possible that this can induce $BITMAP corruption, but even this is rare. You might find relevant errors in your Windows System Event log to aide troubleshooting. 


Kind Regards

Nick - Macrium Support

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