On Wed, Jul 11, 2012 at 11:20:16AM -0500, Mark Nipper wrote: > Just as a sanity check for our own setup, write > performance out of the box with KVM (managed via libvirt) is > awful, like less than 5MB/s because the disk cache mode is set to > none by default. Same as what I see. > But changing this to writeback or writethrough is still > considered acceptable and safe, correct? cache=writethrough is the default (slow) mode, and is safe. cache=writeback is is positively unsafe, and only acceptable if you don't care about possible data loss. http://www.linux-kvm.org/wiki/images/5/59/Kvm-forum-2011-performance-improvements-optimizations-D.pdf "Cache=writeback - Not supported" > But my understanding from reading previous posts on this > list is that using something other than a cache mode of none is > acceptable and safe with Gluster at least. cache=none is definitely what we want, but doesn't currently work with glusterfs. Regards, Brian.
