Compact and truncate MFT

[BloodySword]

Paragon Total Defrag ( http://www.paragon-software.com/home/total-defrag/) has a Compact & truncate MFT feature. What do you think of it? Would it be possible for MyDefrag? Would it be save? (crash / power failue)

[quanthero]

I tried this feature in PTD a long time ago when, for some weird reason, my MFT was like 1GB and only 10% of it was occupied. Everything worked well.

However, I think implementing this in MyDefrag will be too complicated and time consuming. First of all, MFT cannot be compacted and truncated while Windows is running, so some kind of pre-boot module is required. Secondly, the program has to do it 'manually' (i.e. there are no API calls in Windows which can accomplish that, etc.), so programming involved in developing such feature is certainly complicated and time-consuming. But this is just my opinion. It would be interesting to know what are Jeroen's thoughts on this idea.

[BloodySword]

Yes but this feature would be quite interesting. I would like to test it with a usb stik formatted with NTFS. Adding and deleting files and watching the MFT occupiation and testing how MyDefrag is able to optimize this and see if there are problems or MFT corruption.

[jeroen]

I agree that it would be a useful feature. But as quanthero has already said it would be difficult to build. And it would be dangerous. Microsoft has published the structure of FAT, but not of NTFS. There is a lot of reverse-engineered information on the internet, enough for me to have build the MFT scanner in MyDefrag, but not enough to even think about shrinking the MFT.

[BloodySword]

When MyDefrag would be open source, perhaps there are some programmers wich would test such a feature. Why is MyDefrag closed source?

[Kasuha]

If I remember it correctly, jkDefrag was open source and Jeroen expected that a developer community will grow around it but it did not happen, instead other defragger authors started using parts of jkDefrag code in their (paid) products.

My opinion regarding MFT internal optimization is, unless Microsoft publishes API functions for it, MyDefrag should leave it as is. I also think that for majority of people MFT size and fill factor is not an issue.

[Leolo]

Does anyone know what exactly is this "compact and truncate" feature?

The closest thing to a description I could find is this:

http://support.microsoft.com/kb/814594

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. Currently, only third-party defragmenters consolidate unused MFT FRS records and reclaim unused MFT allocated space.

Is that what Paragon refers to as "compact and truncate"?

[jonib]

Is that what Paragon refers to as "compact and truncate"?

Yes.

jonib