Re: finobt option for end user

[Alphazo <alphazo@xxxxxxxxx>]

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@xxxxxxxxxxxxx> 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@xxxxxxxxxxxxx