Re: [ros-dev] FullFAT replacement for Fastfat.sys

[Aleksey Bragin]

I'll explain the FAT journalling part, it's the idea I had for quite  
a while, and mainly it's just an experimental, fun idea.
So far FAT provides no consistency of neither metadata nor actual  
data. In order to maintain consistency, the filesystem's integrity  
has to be verified and fixed at every boot if not clean shutdown is  
detected.

Now, if we add a special file, let's say our driver knows its  
placement for sure, and that file doesn't change size and is not  
movable, we can implement transactional writing of metadata to the  
FAT directory entries using this file as a journal.
Advantages:
- Compatibility with original FAT drivers (without journalling of  
course)
- Metadata is always consistent (no need for a checkdisk).
Disadvantages:
- Please name them.

I suppose that's how ext3 was done from ext2. Why making the same  
from FAT would be a bad idea?

WBR,
Aleksey Bragin.

On Jul 30, 2009, at 1:52 AM, Pierre SCHWEITZER wrote:

>   Hi,
>
>  "I'm still at a loss as to why you are all ignoring the free, open  
>  source, FastFAT driver in the Microsoft WDK.". Wasn't it some kind  
>  a license problem? EULA, or something like that? The question rose  
>  when ARM ninjas imported CDFS driver from the Microsoft WDK. They  
>  finally had to remove it. Anyway, that's not exactly the point.
>
>  Regarding your initial question, for FSD an important part is  
>  missing in ReactOS: FsRTL package. Moreover, you may (or, you  
>  will?) have problems using CC package. But, that's a good point in  
>  fact. That way, we'll be able to implement/debug the needed  
>  functions, with test case.
>
>  Finally, I'd like to come back on that idea: "During the  
>  conversation we also discussed implementing a special journaling  
>  extension to FullFAT via the windows driver.". I've to admit I  
>  don't see how it can be a good idea. IF everything goes well,  
>  ReactOS will be able to handle two journalised FS: NTFS and ext3.  
>  Those are known, and used FS. Why should we create a "super" FAT  
>  instead of using those FS? What about compatibilty?
>  A better idea would to handle exFAT...
>
>  Best regards,
>  P. Schweitzer
>
>  From: ionucu(a)videotron.ca
>  To: ros-dev(a)reactos.org
>  Date: Wed, 29 Jul 2009 14:00:08 -0700
>  Subject: Re: [ros-dev] FullFAT replacement for Fastfat.sys
>
>  I'm still at a loss as to why you are all ignoring the free, open  
>  source, FastFAT driver in the Microsoft WDK.
>
>  On 29-Jul-09, at 10:56 AM, Gabriel ilardi wrote:
>
>  Hi James,
>
>  Welcome to the team!
>  ReactOS kernel aims to be compatible with W2k3's, meanwhile Win32  
>  subsystem aims atm Vista.
>  You'll come across missing stuff, just search for UNIMPLEMENTED  
>  throughout the code. Encoded started a page with missing  
>  functionality here:http://www.reactos.org/wiki/ 
>  Missing_ReactOS_Functionality
>  Hope you have fun with ReactOS as much as we do...
>
>  Gabriel ilardi.
>
> >   Date: Wed, 29 Jul 2009 13:59:42 +0200
> >  From: james(a)worm.me.uk
> >  To: ros-dev(a)reactos.org
> >  Subject: [ros-dev] FullFAT replacement for Fastfat.sys
> >
> >  Hi Everyone,
> >
> >  I just thought I'd introduce myself. I am the author of a new FAT
> >  implementation that was really designed for embedded systems. As   
>  such
> >   it provides very good performance. (See
> > www.fullfat-fs.co.uk).
> >
> >  Fireball contacted me a few days ago to discuss the current
> >  development of FullFAT, and since I have agreed to implement an IFS
> >  driver based on FullFAT with a view to replacing the current
> >  fastfat.sys implementation. During the conversation we also   
>  discussed
> >   implementing a special journaling extension to
> > FullFAT via the   
>  windows
> >   driver.
> >
> >  I hope to start work on this project in the next few weeks, and
> >  further to this I would also like to help in some other areas of
> >  ReactOS. I shall be taking a closer look at the ReactOS code over   
>  the
> >   coming weeks, and will probably post some
> > questions about various
> >  aspects. I have just bought the Windows Internals, fifth edition
> >  co-authored by Alex Ionescu, hopefully this will provide me with a
> >  good overview of the Windows architecture etc.
> >
> >  For complete Windows XP compatibility, just how much of the
> >  implementation is currently missing from ReactOS?
> >
> >  Nice to meet you all, and I hope to provide some good   
>  contributions to
> >   ReactOS in the near future.
> >
> >  James
> >
> >  --
> >  James Walmsley
> >  ----------------------------------------
> >  james(a)worm.me.uk
> >
> >  _______________________________________________
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> >  Ros-dev(a)reactos.org
> >  http://www.reactos.org/mailman/listinfo/ros-dev 
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>
>  Best regards,
>  Alex Ionescu
>
>