MFT and File Ids

NTFSD
1

I’m trying to reconcile a few seemingly disparate pieces of info regarding
the MFT size and File Ids. The W2k Resource Kit indicates that the
maximum number of objects in an NTFS volume is 2^32-1 (I’m not sure how
that number is derived). File Ids leave room for 2^48 unique files on the
volume. What is the explanation for the mismatch? Either:

  1. 2^32-1 is not really the limit of NTFS objects.
  2. bits 32-47 of the File Id are not used.
  3. MFT indexes can extend past 2^32. This would imply that there is a max
    object counter somewhere in NTFS that limits ‘active’ MFT records to 2^32.
    It would also imply that the MFT could grow to an enormous size, although
    it was hinted at earlier in ntfsd that the MFT can be made sparse.
  4. something else?

I realize that all of these limits are theoretical but it potentially
impacts how objects can be uniquely identified on NTFS.

2

The answer is that every MFT-entry is at least 2^10 =1024 bytes long.
And I think it may be up to 64kb which would fill up your bits in terms
of maximum file size. Also MFT is just a file.

xxxxx@the1vision.com schrieb:

I’m trying to reconcile a few seemingly disparate pieces of info regarding
the MFT size and File Ids. The W2k Resource Kit indicates that the
maximum number of objects in an NTFS volume is 2^32-1 (I’m not sure how
that number is derived). File Ids leave room for 2^48 unique files on the
volume. What is the explanation for the mismatch? Either:

  1. 2^32-1 is not really the limit of NTFS objects.
  2. bits 32-47 of the File Id are not used.
  3. MFT indexes can extend past 2^32. This would imply that there is a max
    object counter somewhere in NTFS that limits ‘active’ MFT records to 2^32.
    It would also imply that the MFT could grow to an enormous size, although
    it was hinted at earlier in ntfsd that the MFT can be made sparse.
  4. something else?

I realize that all of these limits are theoretical but it potentially
impacts how objects can be uniquely identified on NTFS.

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