[libvirt-users] qcow2 performance

Greets, I have to research performance-issues of a W2003-VM within KVM. Right now it's a qcow2-image-file w/ default settings within libvirt (configured by vmm ...) My question: what caching to use? writeback/writethrough/etc ... what to use for data integrity while not getting ultraslow performance? Found https://www.linuxfoundation.jp/jp_uploads/JLS2009/jls09_hellwig.pdf Is there any other list/doc what to use and why? Thanks, Stefan