On Sat, Jun 09, 2012 at 09:53:05AM +0100, Brian Candler wrote: > So clearly cache='none' (O_DIRECT) makes a big difference when using a > local filesystem, so I'd very much like to be able to test it with gluster. Aha, O_DIRECT is in 3.4+: http://comments.gmane.org/gmane.comp.file-systems.gluster.user/8916 http://lwn.net/Articles/476978/ So I upgraded this box to a mainline 3.4.0 kernel from http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.4-precise/ After this: * KVM *does* boot with the cache='none' option :-) * However performance is pretty much unchanged :-( ubuntu at lucidtest:~$ dd if=/dev/zero of=/var/tmp/test.zeros5 bs=1024k count=500 500+0 records in 500+0 records out 524288000 bytes (524 MB) copied, 10.184 s, 51.5 MB/s (As a reminder: that's KVM talking to a single-brick gluster volume, FUSE-mounted on the same node. Other tests showed 248MB/s with KVM guest talking to the RAID10 array directly, and 350MB/s with the host talking to the RAID10 array directly) Regards, Brian.
