I've written about this before, but since we still receive questions or comments on this topic, I'm doing so again as a review. Uses sometimes ask us why PerfectDisk does not change the size of the Master File Table (MFT). Other defragmenters do it and, hey, changing something seems pretty cool. Well, this is another area where we think PerfectDisk is a little smarter.
When an NTFS drive is formatted, it creates the $MFT, which contains a fixed number of records which can used. As files are created, these records are used. Eventually, the pre-allocated number of records is filled up and the $MFT needs to grow, adding another chunk of file records. Immediately adjacent to the $MFT, the MFT Reserved Zone is created. By default, the MFT Reserved Zone is 12.5% of the drive and goes from the first record of the MFT to the first non-free cluster after the last MFT record. If you have a 100GB drive, then the Reserved Zone is going to be 12.5GB - quite large! If you look in the Windows Explorer/Properties on a drive, the free space shown is the total of both INSIDE and OUTSIDE the Reserved Zone.
The MFT Reserved Zone is created specifically to allow the $MFT to grow in a contiguous fashion. When the $MFT fills up, it allocates the next chunk from the free space located in the MFT Reserved Zone. NTFS will avoid putting files inside the Reserved Zone unless you get into a low free space condition. It is not necessary to artificially pre-allocate additional space for the $MFT in order to keep it from growing fragmented.
A smarter MFT means a smarter defrag.
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