This is fixed by commit a3548077062dd9dc2701ebffd931ba6eaef40bec which is included in 1.3 release of qemu.
** Changed in: qemu Status: Confirmed => Fix Released -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1071236 Title: creating qcow2 image with preallocation fails if size >=4G Status in QEMU: Fix Released Bug description: Steps to reproduce: 1. run> qemu-img create -f qcow2 -o cluster_size=512,preallocation=metadata disk.img 4G Reproducible: Always Configuration: Gentoo Linux 3.4.9, 64b latest qemu available from portage (afaik this is pulled from the git repo) Possible workarounds: 1. ommit preallocation= 2. increase cluster_size 3. reduce the image size Although workarounds are available, it is still a bug that could (and should) be fixed. To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1071236/+subscriptions