What is "Reserved System Space" and what can I do with it?

[Cyril N. Alberga]

I'm running XP Pro, SP2.

I recently did two things.

First, I took a 250 GByte FAT external harddrive, backed it contents up to
another drive and reformatted it as NTFS, then restored the contents.

Second, I installed an incremental defrag program, Diskeeper, on my system.
When I looked at the newly reformatted drive Diskeeper reports that over 10% is
"Reserved System Space". This is an order of magnitude more than on any of my
other 250 or 300 Gbyte drives, or even my one 500 Gbyte drive.

Could this be an error in the defrag program? (The company says no.) If such a
large chunk of the drive is reserved does that mean that it will never be used
for my data? Is there any way to shrink this allocation?

I hope this is the right place to ask this.

Cyril N. Alberga

 

[DL]

No its not an error, its referering to the Master File Table, MFT
If you check Diskkeeper options there should be one to configure the MFT, if
required
NB This is not avilable in Diskeeper Home Edition

 

[JS]

See: http://answers.google.com/answers/threadview?id=780063

JS

 

[Cyril N. Alberga]

Sadly, that is what I have. If I were to repeat my backup/format/restore is
there a way to persuade XP to make a more reasonable allocation?

Cyril

 

[Cyril N. Alberga]

Thank you -- I think... I followed the instructions, there were 12% of the disk
reserved, and I pushed it down to 1% (a bit over 1 gig). But diskeeper still
thinks there is a hugh chunk. Do I have to shutdown and restart before I see
the effects?

Cyril

 

[JS]

Don't know as I'm no longer running Disk Keeper.
Reboot and see if it DK reports the correct value.

JS

 

[DL]

You say your hd's are 250, 300 & 500gb
The reserved space will vary on each one at 12% your 500 will have approx
60gb
You dont combine the MFT's sizes
Lowering the MFT could lead to file/sys problems
Because the space is 'reserved' doesnt meant it cannot be used

 

[John John]

You can't push the MFT Zone reservation to 1%. The
NtfsMftZoneReservation is set in the registry, possible values for the
entry and the corresponding reserved space are:

1 = 12.5%
2 = 25%
3 = 37.5%
4 = 50%

You already have this set to the lowest possible value.

Because MFT fragmentation can degrade performance the file system
preemptively reserves a large contiguous block for the MFT when the
drive is formatted. This space isn't lost, it will be used when needed.
If the disk runs out of space for files the file system will relent
and yield space for the files from the MFT zone. The opposite is also
true, if the MFT zone fills up it will take space from the available
(free) disk space for its needs. When either of these happen the MFT
will become fragmented and the built in disk defragmenter will not be
able to defragment it. Also note that small files of 1KB or less are
stored in the MFT.

John

 

[Cyril N. Alberga]

Perhaps I see what is happening then. All the disks were set to 12%, which is
the highest that "My Computer" seems to allow, while 1% is the lowest. I had
tried the 1% values based on someone up-thread saying that 750 Mbytes (I think)
should be sufficient, and 1% gave over 2 Gbytes. My confusion was based on the
fact that all the other disks had much smaller areas marked as "reserved", even
though they are shown as 12% in the "property" box. I suppose the space has
been used for data files, as most of the disks are fairly full.

Thanks to everyone who has helped clear up my puzzlement.

Cyril

 

[MAP]

Perhaps I see what is happening then. All the disks were set to 12%,
which is the highest that "My Computer" seems to allow, while 1% is
the lowest. I had tried the 1% values based on someone up-thread
saying that 750 Mbytes (I think) should be sufficient, and 1% gave
over 2 Gbytes. My confusion was based on the fact that all the other
disks had much smaller areas marked as "reserved", even though they
are shown as 12% in the "property" box. I suppose the space has been
used for data files, as most of the disks are fairly full.
Thanks to everyone who has helped clear up my puzzlement.

Cyril

Do not confuse the MFT with system restore.

 

[Gerry]

MAP

He already has <G>.


--
Regards.

Gerry
~~~~
FCA
Stourport, England
Enquire, plan and execute
~~~~~~~~~~~~~~~~~~~

 

[foppe de Haan]

why the hell does it have to be at least 12%? every entry is roughly 1kb, so even with 1m files on a disk you require only 1gb of MFT space.. and having 60gb 'reserved' space on a 500GB drive is absolutely ridiculous, and wreaks havoc on defragmentation efficiency of near-full drives.

 

[John John (MVP)]

Because MFT fragmentation can degrade performance the file system
preemptively reserves a large contiguous block for the MFT when the
drive is formatted. This space isn't lost, it will be used if needed. If
the disk runs out of space for files the file system will relent and
yield space for the files from the MFT zone. The opposite is also true,
if the MFT zone fills up it will take space from the available (free)
disk space for its needs, the problem there is that in both instances
the MFT will become fragmented and the built in disk defragmenter will
not be able to defragment it. Also note that small files of 1KB or less
are stored in the MFT.

John

why the hell does it have to be at least 12%? every entry is roughly

1kb, so even with 1m files on a disk you require only 1gb of MFT space..
and having 60gb 'reserved' space on a 500GB drive is absolutely
ridiculous, and wreaks havoc on defragmentation efficiency of near-full
drives.

 

[Gerry]

NTFS Master File Table (MFT) Expansion
When an NTFS volume is created and formatted, NTFS metafiles are
created. One of these metafiles is named the Master File Table (MFT). It
is very small when it is created (approximately 16 KB), but it grows as
files and folders are created on the volume. When a file is created, it
is entered in the MFT as a File Record Segment (FRS). The FRS is always
1024 bytes (1 KB). As files are added to the volume, the MFT grows.
However, when files are deleted, the associated FRSs are marked as free
for reuse, but the total FRSs and associated MFT allocation remains.
That is why you do not regain the space used by the MFT after you delete
a large number of files, .

To see exactly how large the MFT is, you can use the built-in
defragmenter to analyze the volume. The resulting report provides
detailed information about the size and number of fragments in the MFT.

For example:
Master File Table (MFT) fragmentation
Total MFT size = 26,203 KB
MFT record count = 21,444
Percent MFT in use = 81 %
Total MFT fragments = 4

However, for more complete information about how much space (overhead)
the whole NTFS is using, run the chkdsk.exe command, and then view the
output for the following line:
In use by system.

Currently, only third-party defragmenters consolidate unused MFT FRS
records and reclaim unused MFT allocated spaceNTFS MFT Expansion
http://support.microsoft.com/kb/315688
http://support.microsoft.com/kb/814594

Reserved space. Further reading:
http://msdn.microsoft.com/en-us/library/aa365230(VS.85).aspx
http://support.microsoft.com/kb/174619

--



Hope this helps.

Gerry
~~~~
FCA
Stourport, England
Enquire, plan and execute
~~~~~~~~~~~~~~~~~~~

 

[richard]

NTFS Master File Table (MFT) Expansion
When an NTFS volume is created and formatted, NTFS metafiles are
created. One of these metafiles is named the Master File Table (MFT). It
is very small when it is created (approximately 16 KB), but it grows as
files and folders are created on the volume. When a file is created, it
is entered in the MFT as a File Record Segment (FRS). The FRS is always
1024 bytes (1 KB). As files are added to the volume, the MFT grows.
However, when files are deleted, the associated FRSs are marked as free
for reuse, but the total FRSs and associated MFT allocation remains.
That is why you do not regain the space used by the MFT after you delete
a large number of files, .

To see exactly how large the MFT is, you can use the built-in
defragmenter to analyze the volume. The resulting report provides
detailed information about the size and number of fragments in the MFT.

For example:
Master File Table (MFT) fragmentation
Total MFT size = 26,203 KB
MFT record count = 21,444
Percent MFT in use = 81 %
Total MFT fragments = 4

However, for more complete information about how much space (overhead)
the whole NTFS is using, run the chkdsk.exe command, and then view the
output for the following line:
In use by system.

Currently, only third-party defragmenters consolidate unused MFT FRS
records and reclaim unused MFT allocated spaceNTFS MFT Expansion
http://support.microsoft.com/kb/315688
http://support.microsoft.com/kb/814594

Reserved space. Further reading:
http://msdn.microsoft.com/en-us/library/aa365230(VS.85).aspx
http://support.microsoft.com/kb/174619

My MTF files is 77MB. Just curious as to how large that is compared to
others' MTF size.

 

[Gerry]

Richard

foppe de Haan is complaining about the amount of reserved space ( 12.5%
of the six=ze of the partition / drive) not the amount actually being
used by the MFT.

The MFT on my Windows partition is 79 mb. However, I have a number of
partitions, each with it's own MFT. There is a direct correlation
between the number of files and folders and the size of the MFT.

--



Hope this helps.

Gerry
~~~~
FCA
Stourport, England
Enquire, plan and execute
~~~~~~~~~~~~~~~~~~~