On Wed, Oct 01, 2008 at 05:13:31PM -0300, Peter Cordes wrote:
> On Wed, Oct 01, 2008 at 09:36:13PM +0200, Andi Kleen wrote:
> > Peter Cordes <peter@xxxxxxxxx> writes:
> > >
> > > XFS knows (or should have been told by the admin with mkfs!) what the
> > > stripe geometry is: block size and stripe width. So it could apply
> > > this optimization only if it would make a write cover more whole
> > > blocks or whole stripes.
> > It's a nice idea, but I don't think XFS knows the actual RAID level,
> > only the stripes. And for 0/1 it wouldn't be a good idea.
> Yeah, this would have to be a mount option, like stripewrite=1.
> There are already a few other essential mount options people need to
> learn about for big RAIDs, e.g. inode64.
The other problem I can think of is that determing if something is
free data might need more read IO if the free extent tree is not completely