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[Xen-users] disk speed

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Subject: [Xen-users] disk speed
From: "Sebastian Reitenbach" <sebastia@xxxxxxxxxxxxxxxxxxxx>
Date: Mon, 22 Oct 2007 14:12:39 +0200
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Reply-to: Sebastian Reitenbach <sebastia@xxxxxxxxxxxxxxxxxxxx>
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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

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