Open Stack

> from above numbers it doesn't sound like storage node is the culprit -
> 50% drop happens on compute node going from baremetal to virtual. So I'm
> inclined to think it's a tuning of virtio (if that is even possible).

Some tuning tips for kvm: http://www.linux-kvm.org/page/Tuning_KVM

We saw a major improvement using RAW vs QCOW2 
(in theory this should be similar, however, when you need a high random IO throughput we did see major improvements in our setup with RAW)

On more thing to check is partition alignment. (not very likely for a recent OS)


Cheers,
Robert van Leeuwen