"Reserved for MFT"?

John

Don't forget that the Microsoft Disk Defragmenter is a cut down version
of an earlier version of Diskeeper.

References to mirror:

http://www.ntfs.com/ntfs-mft.htm
http://www.webopedia.com/TERM/M/MFT.html

Diskeeper leaves a small portion of system files (green files) in the
middle of the drive.

That second bit of green in the middle of the disk is the MFT Mirror.
The first dozen or so blocks of the MFT (Master File Table) are
critical; if you lose them, you lose everything on the drive. Those
blocks are duplicated in the MFT Mirror, which is positioned in the
middle of the disk. This makes it very difficult to lose both copies.
You may have noticed that the MFT always has at least two fragments; you
can't get it to one fragment. That extra fragment usually represents the
MFT Mirror.
Source:
http://support.diskeeper.com/support/diskeeperfaqs.aspx?Page=5&Subpage...cust=1&


~~~~


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

John John (MVP) wrote:
> How about the built-in Windows defragmenter? Are you saying that it
> treats the $MFT and the $MFTMirr as one file and that that is why the
> built-in defragmenter always shows it (the MFT) as being in two
> segments?
> John
>
> DiskeeperRep wrote:
>
>> Hi,
>>
>> The second fragment of the $MFT is the MFT mirror.
>> http://tinyurl.com/63hw8o
>>
>> I'll copy-paste the relevant passage from the 'Analysis and
>> Defragmentation' section.
>>
>> - That second bit of green in the middle of the disk is the MFT
>> Mirror. The first dozen or so blocks of the MFT (Master File Table)
>> are critical; if you lose them, you lose everything on the drive.
>> Those blocks are duplicated in the MFT Mirror, which is positioned
>> in the middle of the disk. This makes it very difficult to lose both
>> copies. You may have noticed that the MFT always has at least two
>> fragments; you can't get it to one fragment. That extra fragment
>> usually represents the MFT Mirror.-
>>
>> Hope this helps
>> Best regards
>> -------------------
>> Representative
>> Diskeeper Corporation
>> ---------------------
>>
>> Gerry;3164363 Wrote:
>>
>>> John
>>>
>>> My feeling is that an MFT in two fragments is par for the course. I
>>> feel
>>> sure I got an explanation from Greg Hayes some years ago why this
>>> is so but I can now no longer find or remember the explanation he
>>> gave. On
>>> this system I have three fragments on the C partition and two on the
>>> other partitions.
>>>
>>>
>>> ~~~~
>>>
>>>
>>> Gerry
>>> ~~~~
>>> FCA
>>> Stourport, England
>>> Enquire, plan and execute
>>> ~~~~~~~~~~~~~~~~~~~
>>>
>>>
>>>
>>> John John (MVP) wrote:-
>>> Actually there are two things at work on Windows XP. The first one
>>> is
>>> that on XP the MFT is apparently just an NTFS-hint, it no longer
>>> reserves large contiguous blocks for the MFT and the defragmenter
>>> can defrag in and out of the MFT. That is the theory... but in
>>> practice it doesn't always work like that. This is still fairly
>>> new to me but my findings have been that there may still be a
>>> minimum of 12.5% of the drive reserved for the MFT zone on Windows
>>> XP installations and that when (if) there is no such large reserved
>>> zone (NTFS-hint) the defragmenter still does not fully defragment
>>> the MFT, I have seen it in two fragments in my test and I can run
>>> defrag in GUI or command-line mode until the cows come home and the
>>> MFT is still left in two fragments. Documentation on this is scant
>>> and I haven't done extensive testing so I don't know what exactly
>>> is going on with this. I think that the differences may be whether
>>> the drive is formatted by the XP setup program or whether it is
>>> formatted by an up and running XP installation. This is just a
>>> guess, I haven't had time to do more test on this. Greg from Raxco
>>> could probably shed more light on this but I haven't seen him in
>>> the groups for a little while... John
>>>
>>> Gerry wrote:
>>> -
>>> John
>>>
>>> I am not sure I can reconcile your last paragraph with this extract
>>> from KB 227463
>>>
>>> In Windows 2000, it does not defragment NTFS metadata files, such as
>>> the Master File Table (MFT), or the metadata that describes a
>>> directory's contents. This limitation has been removed in Windows XP
>>> and later. It cannot defragment encrypted files in Windows 2000.
>>> This limitation has been removed in Windows XP and later.
>>> Disk Defragmenter Limitations in Windows 2000, Windows XP, and
>>> Windows Server 2003
>>> http://support.microsoft.com/kb/227463
>>>
>>>
>>> ~~~~
>>>
>>>
>>> Gerry
>>> ~~~~
>>> FCA
>>> Stourport, England
>>> Enquire, plan and execute
>>> ~~~~~~~~~~~~~~~~~~~
>>>
>>>
>>> John John (MVP) wrote:
>>> -
>>> Jim wrote:
>>>
>>>
>>> While defragging my C: drive, there is a pretty large sector
>>> saying Reserved For MFT. Can anyone explain just what
>>> that space is needed for?
>>>
>>> It's reserved space for the Master File Table. The MFT is one of
>>> the most important files on your hard disk, each file on the disk is
>>> recorded in the MFT, the operating system uses the MFT to find your
>>> files and to record information about the files.
>>>
>>> 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 ---

Yes, I know that.

John

Gerry wrote:

> John
>
> Don't forget that the Microsoft Disk Defragmenter is a cut down version
> of an earlier version of Diskeeper.
>
> References to mirror:
>
> http://www.ntfs.com/ntfs-mft.htm
> http://www.webopedia.com/TERM/M/MFT.html
>
> Diskeeper leaves a small portion of system files (green files) in the
> middle of the drive.
>
> That second bit of green in the middle of the disk is the MFT Mirror.
> The first dozen or so blocks of the MFT (Master File Table) are
> critical; if you lose them, you lose everything on the drive. Those
> blocks are duplicated in the MFT Mirror, which is positioned in the
> middle of the disk. This makes it very difficult to lose both copies.
> You may have noticed that the MFT always has at least two fragments; you
> can't get it to one fragment. That extra fragment usually represents the
> MFT Mirror.
> Source:
> http://support.diskeeper.com/support/diskeeperfaqs.aspx?Page=5&Subpage...cust=1&
>
>
> ~~~~
>
>
> Gerry
> ~~~~
> FCA
> Stourport, England
> Enquire, plan and execute
> ~~~~~~~~~~~~~~~~~~~
>
> John John (MVP) wrote:
>
>>How about the built-in Windows defragmenter? Are you saying that it
>>treats the $MFT and the $MFTMirr as one file and that that is why the
>>built-in defragmenter always shows it (the MFT) as being in two
>>segments?
>>John
>>
>>DiskeeperRep wrote:
>>
>>
>>>Hi,
>>>
>>>The second fragment of the $MFT is the MFT mirror.
>>>http://tinyurl.com/63hw8o
>>>
>>>I'll copy-paste the relevant passage from the 'Analysis and
>>>Defragmentation' section.
>>>
>>>- That second bit of green in the middle of the disk is the MFT
>>>Mirror. The first dozen or so blocks of the MFT (Master File Table)
>>>are critical; if you lose them, you lose everything on the drive.
>>>Those blocks are duplicated in the MFT Mirror, which is positioned
>>>in the middle of the disk. This makes it very difficult to lose both
>>>copies. You may have noticed that the MFT always has at least two
>>>fragments; you can't get it to one fragment. That extra fragment
>>>usually represents the MFT Mirror.-
>>>
>>>Hope this helps
>>>Best regards
>>>-------------------
>>>Representative
>>>Diskeeper Corporation
>>>---------------------
>>>
>>>Gerry;3164363 Wrote:
>>>
>>>
>>>>John
>>>>
>>>>My feeling is that an MFT in two fragments is par for the course. I
>>>>feel
>>>>sure I got an explanation from Greg Hayes some years ago why this
>>>>is so but I can now no longer find or remember the explanation he
>>>>gave. On
>>>>this system I have three fragments on the C partition and two on the
>>>>other partitions.
>>>>
>>>>
>>>>~~~~
>>>>
>>>>
>>>>Gerry
>>>>~~~~
>>>>FCA
>>>>Stourport, England
>>>>Enquire, plan and execute
>>>>~~~~~~~~~~~~~~~~~~~
>>>>
>>>>
>>>>
>>>>John John (MVP) wrote:-
>>>>Actually there are two things at work on Windows XP. The first one
>>>>is
>>>>that on XP the MFT is apparently just an NTFS-hint, it no longer
>>>>reserves large contiguous blocks for the MFT and the defragmenter
>>>>can defrag in and out of the MFT. That is the theory... but in
>>>>practice it doesn't always work like that. This is still fairly
>>>>new to me but my findings have been that there may still be a
>>>>minimum of 12.5% of the drive reserved for the MFT zone on Windows
>>>>XP installations and that when (if) there is no such large reserved
>>>>zone (NTFS-hint) the defragmenter still does not fully defragment
>>>>the MFT, I have seen it in two fragments in my test and I can run
>>>>defrag in GUI or command-line mode until the cows come home and the
>>>>MFT is still left in two fragments. Documentation on this is scant
>>>>and I haven't done extensive testing so I don't know what exactly
>>>>is going on with this. I think that the differences may be whether
>>>>the drive is formatted by the XP setup program or whether it is
>>>>formatted by an up and running XP installation. This is just a
>>>>guess, I haven't had time to do more test on this. Greg from Raxco
>>>>could probably shed more light on this but I haven't seen him in
>>>>the groups for a little while... John
>>>>
>>>>Gerry wrote:
>>>>-
>>>>John
>>>>
>>>>I am not sure I can reconcile your last paragraph with this extract
>>>>from KB 227463
>>>>
>>>>In Windows 2000, it does not defragment NTFS metadata files, such as
>>>>the Master File Table (MFT), or the metadata that describes a
>>>>directory's contents. This limitation has been removed in Windows XP
>>>>and later. It cannot defragment encrypted files in Windows 2000.
>>>>This limitation has been removed in Windows XP and later.
>>>>Disk Defragmenter Limitations in Windows 2000, Windows XP, and
>>>>Windows Server 2003
>>>>http://support.microsoft.com/kb/227463
>>>>
>>>>
>>>>~~~~
>>>>
>>>>
>>>>Gerry
>>>>~~~~
>>>>FCA
>>>>Stourport, England
>>>>Enquire, plan and execute
>>>>~~~~~~~~~~~~~~~~~~~
>>>>
>>>>
>>>>John John (MVP) wrote:
>>>>-
>>>>Jim wrote:
>>>>
>>>>
>>>>While defragging my C: drive, there is a pretty large sector
>>>>saying Reserved For MFT. Can anyone explain just what
>>>>that space is needed for?
>>>>
>>>>It's reserved space for the Master File Table. The MFT is one of
>>>>the most important files on your hard disk, each file on the disk is
>>>>recorded in the MFT, the operating system uses the MFT to find your
>>>>files and to record information about the files.
>>>>
>>>>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 ---
>
>
>