I like playing with shiny new toys and VDO is one :-) Actually with that it shouldn't matter if whatever is put on top actually has spare allocation in the file format or just blocks with zeros, which makes for a reusable HDD in case I am working with imageio images that are raw. Good to know that using NFS directly won't cost extra performance, because that's how I got around the 4K issue. Alas, plenty of qemu-img imports still fail with the ENOENT error on the 3nHCI gluster. From what I am reading between the lines, oVirt would be rock solid, if somebody didn't want to compete with Nutanix and had put Gluster underneath... With a 25% success rate at trying to transfer VMs from 4.3 to 4.4 I am... in no position to migrate, really. Trying the backup domains next, but their documentation is pretty awful if non-existent.