On 08/15/2011 04:15 PM, Morten Stevens wrote:
> The default settings are bad.
>
> Please tell us more about your settings.

In the libvirtd qemu settings I'm using virtio for disk and net.  Guests are 
Fedora 14+ and SL5/6 using virtio drivers.

I'm using LVM volumes for the disk images, stored on my 8 disk raid10 array.

Had no trouble with exactly the same config in EL5.6.

> Otherwise, I recommend the following points:
>
> - controller: virtio
> - kvm option: cache=none
> - qcow2 disk format with metadata preallocation
> - create your disk image with: qemu-img create -f qcow2 -o
> size=40000000000,preallocation=metadata vdisk.img
>
> Here's a good link to the topic:
> http://www.ilsistemista.net/index.php/virtualization/11-kvm-io-slowness-on-rhel-6.html

Thanks, I'll take a look.




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