Re: [Xen-devel] Which disk backend to use in domU?

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Mon, Jun 14, 2010 at 11:49:45AM +0100, Jeremy Fitzhardinge wrote:
> On 06/11/2010 07:11 PM, Neobiker wrote:
> > Hi
> >
> > Valtteri Kiviniemi-2 wrote:
> >   
> >> Hi, Ah, misunderstanding sorry, you were talking about disk images :)
> >>
> >>     
> > I'm talking about this config:
> > disk        = [
> >                   'phy:/dev/vm/vm01,xvda1,w',
> >                   'phy:/dev/vm/vm01-swap,xvda2,w',
> >                   'phy:/dev/daten/devel_debian_amd64,xvda3,w',
> >               ]
> >   
> 
> file: is definitely unsafe; its IO gets buffered in the dom0 pagecache,
> which means the guests writes aren't really writes.  I believe phy: has
> similar problems, whereas tap:aio: implemented direct IO.  But someone
> more storagey can confirm.
> 

I though phy: submits direct bio's bypassing dom0 pagecache.. 

-- Pasi


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