On Mon, Feb 6, 2012 at 2:07 AM, Stefan G. Weichinger <lists(a)xunil.at&gt; wrote: Sending response back to list incase someone finds it useful. Preallocation works so that when you create a 100GB image it takes up 100GB from the start. This helps performance because without preallocation the disk would only take up space of whatever is stored on it. So each time you add files the filesystem as to grow the image. With qcow2 the preallocation is just metadata. I've found that ls -lh will show the size correctly but something like "df -h" won't reflect the size of those images, nor will "du -h". - Trey