Re: [Xen-users] disk speed

Dan VerWeire
Mon, 22 Oct 2007 16:37:59 -0000

Hi Sebastian,

AFAIK, you should be getting some better results. But most of my experience
is with Windows HVM domUs, so unfortunately I can''t offer you any more
insight into your situation.

Good luck!

Dan

On 10/22/07, Sebastian Reitenbach <sebastia@l00-bugdead-prods.de>
wrote:
>
> 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
> > >