We are using ceph exclusively as a storage backend for our KVM-hosting environment. The number of virtual machines has increased now, but the machines are idle most of the time. However the OSes of the VMs tend to do regular small writes on the disks (I suspect journal commits). As we don't have a lot of disks (only 16 at the moment), this adds up to a high number of write IOPS on the OSD disks with a negligible throughput. What we have in our OSDs are very fast SSD-disks for the ceph journal and I wonder if it would be possible, to delay writes on the disks, until a number of IOPS has been collected in the journal. I think this would improve the situation a lot. Are there any tuning parameters we could use? What would be your suggestion? Thanks, Christian -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
