Fedora xen - Oct 2008 - IO performance sanity check

Hi everyone,

In the dom0 I get about ~120MB/sec sequential write speed to a raid10  
device.

In the domU I get:

	phy to lvm volume on raid10: 22MB/sec
	tap:aio to non-sparse file on raid10: ~22MB/sec

I''ve usually avoided putting anything that needed IO performance on  
Xen, but now I had a few applications that''d fit well in Xen but need  
a little bit of disk IO.   I was surprised just how poorly it works.

Is this kind of performance really what to expect?  Anything  
configuration that can be done to improve it?

Anyone with experience of how the comparable performance with KVM?


  - ask

-- 
http://develooper.com/ - http://askask.com/

Ask Bjørn Hansen wrote:
> I''ve usually avoided putting anything that needed IO performance
on Xen,
> but now I had a few applications that''d fit well in Xen but need a
> little bit of disk IO.   I was surprised just how poorly it works.
My experiences with paravirt Xen have been:

 - Fine performance, as long as "normal" file I/O
   is being used.

 - Bad performance for "low-level" operations like
   file system creation

This was with "raw device" based virtual disks. I haven''t
benchmarked file-
backed virtual disks.

More on my experiences:
http://article.gmane.org/gmane.comp.emulators.xen.user/29483

-- 
Regards,
Troels Arvin <troels@arvin.dk>
http://troels.arvin.dk/