cache=writethrough and cache=none have equivalent data integrity. FWIW, I believe most recent versions of virt-manager default to cache=none for physical devices.
-- LVM backed drives should default to cache='none' https://bugs.launchpad.net/bugs/568445 You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. Status in QEMU: Invalid Status in “virt-manager” package in Ubuntu: Triaged Bug description: Binary package hint: virt-manager KVM guests using LVM backed drives appear to experience fairly high iowait times on the host system if the guest has even a moderate amount of disk I/O. This translates to poor performance for the host and all guests running on the host, and appears to be due to caching as KVM defaults to using writethrough caching when nothing is specified. Explicitly disabling KVM's caching appears to result in significantly better host and guest performance. This is recommended in at least a few places: http://www.mail-archive.com/libvir-l...@redhat.com/msg17492.html http://permalink.gmane.org/gmane.comp.emulators.kvm.devel/48471 http://www.mail-archive.com/k...@vger.kernel.org/msg30425.html http://virt.kernelnewbies.org/XenVsKVM
