Re: [PATCH 1/1] mkfs.xfs fix sunit size on 512e and 4kN disks.

[Christoph Hellwig <hch@infradead.org>]

On Mon, Jun 22, 2026 at 12:05:25PM +0200, Jan Kara wrote:
> > by accident. Properly aligning it to 64k to match its min_io_size is the
> > right thing to do to avoid lots of RMW cycles for once. But I'm pretty
> > sure you already know that :)
> 
> Yes, I agree the XFS logging with the old defaults performed well on that
> machine only due to the battery backed cache.

Which to me suggests it is reporting the wrong min_io_size.  But good
luck getting RAID controller firmware fixed.  Although maybe we should
quirk it in the driver?

> > Well, I don't think 'fsync heavy' applications are the default, or if
> > they are, specially on high-end systems, then I'd argue the application
> > ought to know what it's doing. I do agree that's no universal win
> > anywhere and yet seem to fix the sunit to the hardware reported size is
> > the right thing to do here.
> 
> Fair.

I think the real question is if the value/defaults have any benefits
for this setup.  And I somehow doubt it.