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When I run the standard defragmentation tool on Windows XP, it states that MFT use is 95%. There is a registry key that can set MFT reserve to 12,5% (25, 37,5 etc.), but this requires partition reformatting. These values for percentage of MFT reserve are rather too big, but let that be on the conscience of M$ developers.

I'm concerned on improving disk system perfomance. It seems to me that when the number of files on a partition increase, the MFT will extend to random location on the partition and this will hit the perfomance of disk operations and I will need to defragment the MFT.

I want to enlarge MFT size, but haven't found a way of doing it without reformatting the partition. Is there a tool around for servicing the NTFS MFT?

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This seems like a non-issue. If you need better disk performance add more RAM, Windows will use it as Cache. Also, the disk would be seeing all over the place for the files anyway, so it will have to seek to find the MFT no matter where it is. – Chris S Sep 8 '11 at 12:18
Any links to support information stating that increasing the MFT to other area'a of the disk causes performance issues? Or is this an assumption? – Moab Sep 9 '11 at 3:09

migrated from serverfault.com Sep 8 '11 at 21:11

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A few details here are wrong. The size of each MFT entry is fixed once the drive is formatted. Usually 512 or 1024 bytes, not 4K as suggested here. The actual size of both the entire MFT and each MFT entry is conveniently reported by chkdsk, so there is no need to guess for any actual disk in question.

The percentage reserved through the registry for MFT use is not truly reserved in the sense that the disk fills up more quickly, it is only reserved in the sense that as long as there is at least one free cluster outside the MFT zone, files that grow will grow into those files, not those within the xx% margin from the start of the MFT. This reduces the risk of a fragmented MFT as long as free disk space does not drop below those xx%.

If xx% is set larger than the free space, the risk of a fragmented MFT increases dramatically, even if the MFT is actually much smaller than xx%. If the MFT gets bigger than xx% the same happens. So try to put the xx% selection strictly between the actual MFT size reported by chkdsk and the percentage of free disk space.

Source of Information (comments section) .

Change in Windows XP and in Windows Server 2003: In Windows XP and in Windows Server 2003, the defrag utility defrags the MFT.

Source of Information

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thanks for the tips! "If xx% is set larger than the free space, the risk of a fragmented MFT increases dramatically, even if the MFT is actually much smaller than xx%." – tohaz Sep 9 '11 at 8:21
"If xx% is set larger than the free space, the risk of a fragmented MFT increases dramatically, even if the MFT is actually much smaller than xx%." can not understand the reason for this if it is true. For now i've came up with some kind of solution - 1. Set the registry key for reserve to 12,5% 2. wrote small program that created a lot of small files. The MFT grew. 3. deleted small files. As a result the use of MFT decreased to from 95% to 50%. All a have left is to monitor MFT use... – tohaz Sep 9 '11 at 8:31
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MyDefrag will defrag the MFT and also clear files from the reserve area to allow the MFT to grow.

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Diskeeper can re-size and defragment the MFT.

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I do not need the tool to defragment MFT. downloaded Deskeeper 2011 trial. I see defragment MFT option, but can't find way to resize – tohaz Sep 8 '11 at 12:57
It's called "Frag Shield" – pauska Sep 8 '11 at 13:01

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