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new linux filesystem being developed !


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isn't it ironic ?

microsoft announced a new improved filesysttem for vista

but its permnently being dropped , and there not gonna continue developing it

and r just sticking to ntfs ....

but in the meantime there's a new filesystem being developed for linux :D

its obviously gonna be called ext4 ...

source : http://tinyurl.com/evwaz

Given the recent discussion on LKML two weeks ago, it is clear that many

people feel they have a stake in the future development plans of the

ext2/ext3 filesystem, as it one of the most popular and commonly used

filesystems, particular amongst the kernel development community. For

this reason, the stakes are higher than it would be for other

filesystems. The concerns that were expressed can be summarized in the

following points:

* Stability. There is a concern that while we are adding new

features, bugs might cause developers to lose work.

This is particularly a concern given that 2.6 is a

"stable" kernel series, but traditionally ext2/3

developers have been very careful even during

development series since kernel developers tend to get

cranky when all of their filesystems get trashed.

* Compatibility confusion. While the ext2/3 superblock does

have a very flexible and powerful system for

indicating forwards and backwards compatibility, the

possibility of user confusion has caused concern by

some, to the point where there has been one proposal

to deliberately break forwards compatibility in order

to remove possible confusion about backwards

compatibility. This seems to be going too far,

although we do need to warn against kernel and

distribution-level code from blindly upgrading users'

filesystems and removing the ability for those

filesystems to be mounted on older systems without an

explicit user approval step, preferably with tools

that allow for easy upgrading and downgrading.

* Code complexity. There is a concern that unless the code is

properly factored, that it may become difficult to

read due to a lot of conditionals to support older

filesystem formats.

Unfortunately, these various concerns were sometimes mixed together in

the discussion two months ago, and so it was hard to make progress.

Linus's concern seems to have been primarily the first point, with

perhaps a minor consideration of the 3rd. Others dwelled very heavily

on the second point.

To address these issues, after discussing the matter amongst ourselves,

the ext2/3 developers would like to propose the following path forward.

1) The creation of a new filesystem codebase in the 2.6 kernel tree in

/usr/src/linux/fs/ext4 that will initially register itself as the

"ext3dev" filesystem. This will be explicitly marked as an

CONFIG_EXPERIMENTAL filesystem, and will in affect be a "development

fork" of ext3. A similar split of the fs/jbd will be made in order to

support 64-bit jbd, which will be used by fs/ext4 and future versions

of ocfs2.

2) Bug fixes to fix 32-bit cleanliness issues, security/oops problems

will go into fs/ext3, but all new development work will go into fs/ext4.

There is some question about whether relatively low risk features such

as slimming the extX in-core memory structure, and delayed allocation

for ext3, which have no format impacts, should go into fs/ext3, or

whether such enhancement should only benefit fs/ext4 users. This is a

cost/benefit tradeoff for which the guidance of the LKML community about

whether the loss in code stability is worth the improvements to current

ext3 users, given the existence of the development branch.

In addition, we are assuming that various "low risk" changes that do

involve format changes, such as support for higher resolution

timestamps, will _not_ get integrated into the fs/ext3 codebase, and

that people who want these features will have to use the

stable/development fs/ext4 codebase.

3) The ext4 code base will continue to mount older ext3 filesystems,

as this is necessary to ensure a future smooth upgrade path from ext3

to ext4 users. In addition, once a feature is added to the ext3dev

filesystem, a huge amount of effort will be made to provide continuing

support for the filesystem format enhancements going forward, just as

we do with the syscall ABI. (Emergencies might happen if we make a

major mistake and paint ourselves into a corner; but just as with

changes to the kernel/userspace ABI, if there is some question about

whether or not a particular filesystem format can be supported going

forward indefinitely, we will not push changes into the mainline

kernel until we are can be confident on this point.)

4) At some point, probably in 6-9 months when we are satisified with the

set of features that have been added to fs/ext4, and confident that the

filesystem format has stablized, we will submit a patch which causes the

fs/ext4 code to register itself as the ext4 filesystem. The

implementation may still require some shakedown before we are all

confident that it is as stable as ext3 is today. At that point, perhaps

12-18 months out, we may request that the code in fs/ext3/*.c be deleted

and that fs/ext4 register itself as supporting the ext3 filesystem as


We believe this should satisfy most of the concerns that were

articulated, in particular those that Linus and Jeff were most concerned

about. Comments are of course appreciated.

- Ted

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The ditching of the Microsoft filesystem wouldn't happen to be WinFS, right? That's ancient news, and best I can tell they're still working on it but aren't prograssing quickly enough to make it into Vista.

As for ext4, read this Linux Weekly News article about it:


It does a great job of explaining what the limitation is that ext3 is walking up against, how ext4 intends to fix it, and why such a change needs to result in an ext4 rather than an extention to ext3.

And while ext4 might be nice, you're probably better off with XFS, JFS or Reiser4 if you plan on using BIG filesystems. It's what those filesystems were designed to support from the ground up.

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Jsut to clear up any confusion, WinFS was dropped from Vista along time ago, but only recently was all development on WinFS dropped. WinFS is no more, but M$ has said the work that has been done will be used to improve current file systems. By that I presume they mean we will be getting NTFS with a new coat of paint.

It's certainly not news that the competitors have been way ahead of M$ in file system development for a long time.

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