Re: [Xen-users] disk speed

Sebastian Reitenbach
Mon, 22 Oct 2007 16:22:06 -0000

Hi Dan,

"Dan VerWeire" <dverweire@gmail.com> wrote:

> Are you using PV or HVM DomU''s? If HVM, this may be expected as
the block
> device presented to the DomU is an emulated device in Dom0. Someone
correct
> me if I am wrong please.
>
thanks for your insights. I am running paravirtualized machine, so if I
understand correct, I should get sth. different?

Sebastian

> Dan
>
> On 10/22/07, Sebastian Reitenbach <sebastia@l00-bugdead-prods.de>
wrote:
> >
> > Hi,
> >
> > I started to experiment with xen, so I am still new to it. I was
impressed
> > how easy I got my first virtual node up and running.
> > I measured the disk speed, created a 1gb file with dd.
> > copying that file on the dom0 always took about 5 seconds, on the
domU,
it
> > took about 15-20seconds. I used "time cp large_file
large_file2" to
> > measure
> > the speed. I only expected a small time difference, but not factor
3-4.
> > My virtual disk is a physical device, configured like this:
> > disk=[ ''phy:/dev/sdv2,xvda,w'', ]
> >
> >
> > As far as I know, using the physical partitions as the virtual disk,
> > should
> > be the fastest solution for virtual disks, compared to files.
> >
> > Are there different ways to present a physical partition from dom0 to
a
> > domU, that would influence the speed? Or is the speed factor I have
seen
> > above the one to expect?
> >
> > I am on sles10sp1 x86_64.
> >
> > kind regards
> > Sebastian