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alanx

MFT

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I was checking the MFT on my 12GB partition and noticed it is about 100MB and 90% full.

Then I was reading here

http://www.windowsnetworking.com/kbase/Win...rFileTable.html

(and other places) and read that Windows reserves 12.5% of the partition for the MFT by default. Is this correct?

My questions: why does Windows reserve so much space when so little is actually used?

Is anyone using more than a few percent of their disk volume?

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The reserved space is free, and will be given up if not needed for the MFT.

Fragmentation of the MFT is bad, as it holds the volume's allocation table, as well as small files. For this reason, expansion space is reserved at the tail of the main extent.

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Those 12.5 % aren't wasted space. It's reserved in the sense that it's not written to by Windows until all other space has been exhausted.

I'm just wondering, what happens if you fill your HDD right up to 99% capacity with temporary files doing something like video editing for example. When you delete those temporary files does the MFT get re-instated to its previous state or is it all messed up?

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The MFT itself and the "space reserved for MFT expansion" seem to be two different things. The later can be given up if needed, whereas the MFT itself cannot.

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'all messed up' sounds a bit harsh - but no, it does not get re-instated to its previous state.

Recommened practice is to never fill an NTFS volume to more than about 85-90% of its capacity.

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Never say never! :rolleyes:

On small volumes with lots of tiny files the MFT may even grow above the initial 12.5%.

Don't forget that the fundamental NTFS design is about 10+ years old - so it seems that for 'historical reasons' we do have a registry hack to increase the initial MFT zone size to up to 50% (news feed?), but no easy way to shrink it yet.

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What is "small"?

12GB seems small by today's standards. My 12GB volume contains lots of small files, including the OS, yet still uses less tha 1%.

How much is your volume using?

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Sorry to be picky, but 12 GB = 12000 MB if base 10 is used.

100MB/12000 = 0.008333333... x 100 = 0.833333 % less than 1 %...

What is the complaint about ?

MEJV

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What is "small"?

Next time you're standing in front of a urinal... Oh, never mind!

Small means files that will typically fit in a single cluster. Two examples are the miriad "include" files associated with any large software project and the jillions and jillions of article-files associated with a Usenet newsfeed.

Back when 80 MB was a huge disk (when ntfs was invented), Usenet newsfeeds probably accounted for more sales of big disks than all other applications combined. Of course, back then you could store about a month's worth of articles in 80 MB. :)

--Rick

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Not sure I follow you. I'm not complaining about anything, just curious.

Maybe I should put my question this way.

I noticed that my MFT uses less than 1% of the system volume (<100MB in a 12GB volume).

1. Is this an anomoly? In other words, do most MFTs consume a much greater percentage of the volume?

2. If not, it would seem that the default "reserved space" designated for MFT expansion is set too high at 12.5%, no?

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This reserved space will automatically be used if needed, so it's no problem. I'm just wondering if my system is an anomoly. How much is your volume(s) using, on average?

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I'm not offended by anything. I'm merely wondering if my system is an anomoly.

Don't be offended by my query. Personally, I was offended, and am much happier now that the MFT reserved space on my 160 GB media drives has been reduced from about 20 GB to 500 MB.

-- Rick

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This reserved space will automatically be used if needed, so it's no problem. I'm just wondering if my system is an anomoly. How much is your volume(s) using, on average?

Here's what I have:

PerfectDisk Drive Analysis
Drive C on PANTAGRUEL analyzed on 9/16/2004, 9:51:34 AM 

Entity  Size
------   ----------
MFT     51.9 MB

Free space inside the MFT Reserved zone   4359.6 MB	12 %

---
PerfectDisk Drive Analysis
Drive D on PANTAGRUEL analyzed on 9/16/2004, 9:52:53 AM 

Entity  Size
------   ----------
MFT     66.0 MB

Free space inside the MFT Reserved zone   4346.5 MB	12 %

---
PerfectDisk Drive Analysis
Drive E on PANTAGRUEL analyzed on 9/16/2004, 9:53:37 AM 

Entity  Size
------   ----------
MFT     11.2 MB

Free space inside the MFT Reserved zone  501.8 MB	0 %

---
PerfectDisk Drive Analysis
Drive F on PANTAGRUEL analyzed on 9/16/2004, 9:54:14 AM 

Entity  Size
------   ----------
MFT     54.2 MB

Free space inside the MFT Reserved zone  463.4 MB	0 %

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Seems like your MFTs range in size from 11 to 66 MB. Without volume sizes, I can't calculate percentages, but from your MFT sizes, I don't think they're more than 1% of the volume size.

So it seems like my MFT is normal. Which would indicate that maybe the default 12.5% space reserved for MFT is set a tad high.

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Seems like your MFTs range in size from 11 to 66 MB. Without volume sizes, I can't calculate percentages, but from your MFT sizes, I don't think they're more than  1% of the volume size.

The first two drives are 34GB (Raptors) and the second two are 160GB (Samsungs). Note the wide variability in size of the MFTs wrt the volume size. One thing you can't see in the data I supplied is that the C and D drives only have about 5 GB of data on them, yet their MFTs are far larger than the E drive, which is pushing 150 GB.

That variability is what Microsoft is trying to provide for. If I had the same sort of data-mix on the E drive as I do on C or D, the MFTs would be more like 1.5 GB. Of course, that's still only about 1% of the volume size, not 12.5%.

--Rick

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Yes, a 12.5% MFT zone is absurd today. On small volumes, the most I saw used was under 2%. I've been using sysintern's ntfsinfo for 7 years.

A worse case scenerio might be all files one cluster (4K) with 1K MF record, or 20% for the MFT. With average file size of 40K, that drops to 2%.

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