Is btrfs ready to be default fs in F17 ?

[Alan Cox]

On Sun, 6 Nov 2011 11:20:22 -0300
Fernando Cassia <fcassia at gmail.com> wrote:

> On Sun, Nov 6, 2011 at 07:30, Alan Cox <alan at lxorguk.ukuu.org.uk> wrote:
> 
> > Plus in a funny way btrfs is now in part un-needed,
> 
> 
> Funny how so many people think the btrfs designers are morons.

Funny how some people read strange things into discussions for their own
goals ...

> "In 2008, the principal developer of the ext3<http://en.wikipedia.org/wiki/Ext3>

In 2008 SSDs were basically laboratory dreams or infeasibly expensive toys

> management".[4]<http://en.wikipedia.org/wiki/Btrfs#cite_note-3> Btrfs
> also has "a number of the same design ideas
> thatreiser3<http://en.wikipedia.org/wiki/ReiserFS>

I'd point out two things

1. Wackypedia is not a reference source of any grade, its a sewer of
consensus opinion

2. Reiserfs also had serious problems with fsck handling and stability in
the face of failure cases. It also had a nasty tendancy to degrade in
performance over time. SuSE moved from Reiserfs to ext* having embraced
it as the big new technology of the future and discovering it wasn't.

The reiserfs world really indicates some of the problems. B tree based
file systems ought to be wonderful things. They can do a lot of stuff a
traditional cylinder group based file system cannot do nicely. But
they've also proved to be very fragile, very hard to get right and very
difficult to performance tune for long term stability.

It *can* be done - NetApp have proved that and have done this for years.
Their environment is quite special in some ways but it's a general
purpose fs with snapshots and the like that works.

> BTRfsck is coming along nicely
> http://www.mail-archive.com/linux-btrfs@vger.kernel.org/msg11836.html

It is not production ready. There was a talk covering btrfs fsck stuff in
Prague last week.

> so, let´s cut the FUD, please...

The only FUD source appears to be you right now.

At this point in time btrfs tends to break on sudden power failure cases
or media errors. It has an fsck that just about made 'can do a demo'
status two weeks ago. These are not good attributes for your default file
system.

Yes it'll change eventually perhaps - Oracle, and Red Hat and others
according to Chris Mason are committed to making it work. However using
Fedora users valuable data as cannon fodder is not how it should happen.

I would suggest http://lwn.net/Articles/462543/ is better reading matter
than Wonkypedia.

Even then I suspect for most users ext3/4 is going to continue to be
significantly more robust, easier to fix when it fails, and has a longer
track history under load. I value my data and the ability to recover it
far more than funky snapshotting features.

Alan