finobt option for end user

[Alphazo]

Thanks Dave and Michael for the very informative answers.

I have updated the official ArchLinux XFS wiki page based upon the
information I gathered here so it can benefit to others.

https://wiki.archlinux.org/index.php/XFS#Free_inode_btree

Please do not hesitate to let me know if you see any mistake in my overview.

Cheers,
Alphazo

On Sun, Dec 21, 2014 at 11:18 PM, Dave Chinner <david at fromorbit.com> wrote:

> On Sat, Dec 20, 2014 at 11:52:57PM +0100, Alphazo wrote:
> > Hello,
> >
> > I'm pretty new to XFS. I'm considering moving away from ext4 to XFS
> because
> > of the new self-describing option, performance and reliability
> improvements
> > that XFS went through over the past year. Now I'm puzzled with the new
> free
> > inode btree option (finobt). I tried to find some documentation about it
> > but couldn't find the pros or cons. So from an end-user perspective with
> a
> > couple of TB worth of photos:
> > - Does it improve overall reliability?
>
> No effect on reliability, good or bad.
>
> > - Does it provide faster fsck/repair?
>
> No, if anything, it slows it down because there's more metadata to
> verify and rebuild.
>
> > - Does it improve any read or write operation?
>
> No.
>
> > - Is it safe to use and does it recover as well as with finobt=0?
>
> Yes and yes.
>
> > - What is the typical case for enabling it
>
> It improves performance on aged filesystems i.e. months or years
> down the track when you've added and removed millions of
> files to/from the filesystem.
>
> > and would you recommend using it
> > for any new fs creation?
>
> Consider the fact that "-m crc=1,finobt=1" will be made the mkfs
> default in 3-6 months time - that will probably co-incide with a
> xfsprogs 3.3 release....
>
> Cheers,
>
> Dave.
> --
> Dave Chinner
> david at fromorbit.com
>
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