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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