[Xen-users] disk speed

Sebastian Reitenbach
Mon, 22 Oct 2007 12:12:39 -0000

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