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The default MFT zone is calculated and reserved by the system when it mounts the volume, and is based on volume size. You can increase the MFT zone by means of the registry entry detailed in Microsoft Knowledge Base Article 174619, but you cannot make the default MFT zone smaller than what is calculated. Increasing the MFT zone does not decrease the disk space that users can use for data files.

References

• https://msdn.microsoft.com/en-gb/library/windows/desktop/aa365230%28v=vs.85%29.aspxMSDN: Master File Table