Reserved MFT space


The Analog Kid
I have 2 physical drives both 60gb's on an XP Pro install.

1 is partitioned into 2 drives: 10gb and 46gb
the other is just one partition

Anyways, if I run perfectdisk, each partitions shows alot of space reserved for mft (Shown as "MFT Zone") (on all partitions it's roughly 12% of total space)

Diskeeper show's this as "System Reserved Space"

Any idea what this is and/or for?

At first I thought System Restore, but I only have that turned on for the C: partition and at 8%.

Then I thought Recycle Bin, but I have that set for 5% on each partition.


Glaanies script monkey
Political User
The MFT is the master file table. 12% is normal, and is also why NTFS is really suggested for larger drives.


The Analog Kid
Thanks for the link

But I still don't understand why the MFT is 36 MB, yet the reserved space for the MFT is over 7GB. Can that space be reallocated and used if it is needed?

Perris Calderon

Staff member
Political User
dreamliner77 said:
Thanks for the link

But I still don't understand why the MFT is 36 MB, yet the reserved space for the MFT is over 7GB. Can that space be reallocated and used if it is needed?
that's the master file table zone, not the master file's there to keep a contigous block for future mft

it's a semi container file...not a container file, but almost...nothing is allowed to use the space that is the master file table as long as you ahve plenty of hardrive space available

but once your space becomes scarse, the master file table will allow other files to use the master file table zone

it's a great feature...contiguos block set aside for mft, at no cost in hardrive space

now, I allready said goodnight, and here I am still here

catch everyone later


The Analog Kid
Thanks perris.

That does answer my question

So basically I shouldn't worry bout it. Just wait til I fill the disk up and it will reallocate the space.

Perris Calderon

Staff member
Political User
I need to add more so as to fully explain

beleive it or not, no mft is deleted...the the masterfile table will continue to grow

instead, the os lays the next mft info driectly beside the previous...all mft remains and is not deleted when you delete a file...this is so because deleting mft would prevent the contiguous and consecutive sequence of the master file table

in other words, the master file table will continue to grow

interesting for sure


OSNN Gamer

its a complete and utter waste of space
once a file is removed the corresponding MFT 1kb entry is also removed
new entries are written back in its place
MFT clusters remain active even when empty

I started a little experiment 6 months ago
to see if I could fill the reserved space
& if I could fragment the MFT

I cannot

I created a 1 gig partition for TIF's and maxed out the settings
and just left it
6 months later
& probably a million small files deleted and rewritten

the MFT is in 3 fragments
it started in 2 fragments
the bulk of it is still contiguous
and is only 25 meg in size

who said files on NT don't fragment ?
was that M$ ?
fools !!!!!!

sorry but I still believe NT filing system sucks
hopefully winfs will be an improvement



Perris Calderon

Staff member
Political User
2zee, it's not that ntfs fragments less, it;s that the os doesn't care if it's fragmented, the information in the masterfile table makes seek times less, and performance isn't hurt as much as it is with fat versus the same fragmentation.

anyway, you not being able to fill up the master file table is exactly what happens...the os does stop expanding the mft zone if it needs to stop expanding it

you did prove your point, that the mft zone growing and not deleting old mft looks like it's not unnesseccary, as with your settings, the mft didn't get fragmented even thoguh the mft zone can't grow, and old mft area is re used

here's the ms lowdown;

The NTFS file system contains at its core, a file called the master file table (MFT). There is at least one entry in the MFT for every file on an NTFS volume, including the MFT itself.

Because utilities that defragment NTFS volumes cannot move MFT entries, and because excessive fragmentation of the MFT can impact performance, NTFS reserves space for the MFT in an effort to keep the MFT as contiguous as possible as it grows.

NTFS uses MFT entries to define the files to which they correspond. All information about a file, including its size, time and date stamps, permissions, and data content is either stored in MFT entries or in space external to the MFT but described by the MFT entries.

(Directory entries, external to the MFT, also contain some redundant information regarding files. But a full discussion of all the structures on NTFS is beyond the scope of this article.)

As files are added to an NTFS volume, more entries are added to the MFT and so the MFT increases in size. When files are deleted from an NTFS volume, their MFT entries are marked as free and may be reused, but the MFT does not shrink. Thus, space used by these entries is not reclaimed from the disk.

Because of the importance of the MFT to NTFS and the possible impact on performance if this file becomes highly fragmented, NTFS makes a special effort to keep this file contiguous. NTFS reserves a percentage of the volume for exclusive use of the MFT until and unless the remainder of the volume is completely used up. Thus, space for files and directories is not allocated from this MFT zone until all other space is allocated first.

Volumes with a small number of relatively large files exhaust the unreserved space first, while volumes with a large number of relatively small files exhaust the MFT zone space first. In either case, fragmentation of the MFT starts to take place when one region or the other becomes full. If the unreserved space becomes full, space for user files and directories starts to be allocated from the MFT zone competing with the MFT for allocation. If the MFT zone becomes full, space for new MFT entries is allocated from the remainder of the disk, again competing with other files.

A new registry parameter was introduced in Service Pack 4 for Windows NT 4.0 that can increase the percentage of a volume that NTFS reserves for its master file table. NtfsMftZoneReservation is a REG_DWORD value that can take on a value between 1 and 4, where 1 corresponds to the minimum MFT zone size and 4 corresponds to the maximum. If the parameter is not specified or an invalid value is supplied, NTFS uses a default value of 1 for this parameter

how are you doing in that game thing you have going...are you numver one yet?

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