On Thu, May 20, 2010 at 2:49 PM, Jes Sorensen <jes.soren...@redhat.com> wrote: > On 05/20/10 15:40, Anthony Liguori wrote: >> On 05/20/2010 08:36 AM, Jes Sorensen wrote: >>>> And I strongly suspect that such a blanket change would be wrong but >>>> that a more targeted change like making cache=none default for physical >>>> devices would satisfy mostly everyone. >>>> >>> Is there any other thing than physical devices attached to the -drive >>> parameter? >> >> Image files which are the overwhelming more common use-case. > > For image files we certainly want it too, at least for proper ones (ie. > raw). It could be that it causes problems for qcow2.
Qcow2 is safest with cache=writethrough because it doesn't order image updates: https://bugzilla.redhat.com/show_bug.cgi?id=572825 http://wiki.qemu.org/Features/Qcow2DataIntegrity Stefan