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Re: [Xen-users] Xen and I/O Intensive Loads

On Wednesday 26 August 2009 15:00:39 Javier Guerra wrote:
> On Wed, Aug 26, 2009 at 12:57 PM, Nick Couchman<Nick.Couchman@xxxxxxxxx> 
> > I've changed the dom0 elevator to noop and the domU to deadline.
> shouldn't that be the other way around?

I see what you mean, but it's really what I meant (as described in another 

The noop@dom0 is to lower (the already high) IO latency and leave all 
optimizations to the storage to do, at least in theory.
In _my_ SAN, though, it's still worth using a local IO scheduler (though noop 
is ok).
If you don't have at least a decent hardware-RAID controller with write cache 
enabled, then it's a no-no.

About deadline@domU, that's perhaps even more peculiar.
Apparently. domU pestering dom0 too often with IO requests degrades 
performance, at least in xen 3.0.x.

 Daniel Mealha Cabrita
 Divisao de Suporte Tecnico
 AINFO / Reitoria / UTFPR

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