On 01/13/2013 04:14 AM, glusterzhxue wrote: > Hi all, > We placed Virtual Machine Imame(based on kvm) on gluster file system, > but IO performance of the VM is only half of the bandwidth. > If we mount it on a physical machine using the same volume as the > above VM, physical host reaches full bandwidth. We performed it many > times, but each had the same result. What you're seeing is the difference between bandwidth and latency. When you're writing a big file to a VM filesystem, you're not performing the same operations as writing a file to a GlusterFS mount thus you're able to measure bandwidth. The filesystem within the VM is doing things like journaling, inode operations, etc. that you don't have to do when writing to the client requiring a lot more I/O operations per second, thus amplifying the latency present in both your network and the context switching through FUSE. You have two options: 1. Mount the GlusterFS volume from within the VM and host the data you're operating on there. This avoids all the additional overhead of managing a filesystem on top of FUSE. 2. Try the 3.4 qa release and native GlusterFS support in the latest qemu-kvm. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://supercolony.gluster.org/pipermail/gluster-users/attachments/20130113/7cc6641e/attachment.html>
