Am 06.02.2012 13:26, schrieb Andreas Kurz: > A brief summary about qcow2 performance ... HTH > > http://www.linux-kvm.org/page/Qcow2 thanks -... We are right now testing stuff. I can't set "cache=none" on the productive box ... but it works on my test-box w/ libvirt-0.9.8 and qemu-kvm-0.15.1-r1 (gentoo linux). Significant difference: my testbox runs kernel 3.2.2, productive box 3.0.0 ... could that make the difference? - Things done so far: latest virtio-drivers in w2003-vm deadline scheduler for hdd-IO data=journal for ext4 (ok? think safety) Should I mount the ext4 as ext3 instead? cache=default aio=threads - We are currently trying to figure out if the Windows-clients are the slower part in the game ... checking network etc. Thanks, greets ...