I'm building fedora live images and they use dm-snapshot to make root read-write. The problem I've noticed with this is that either the space allocated for the snapshot is inadequate, or it is generally unstable. My snapshot device is 1048576 512-byte or 512MB. I've used aufs in the past for both a router and desktop and I can generally keep my usage below 512MB.
I'm unable to tell exactly what is consuming all this space, I'm guessing that is the drawback to dm snapshot. Once my system blows past 512MB, it is no longer usable.
Does anyone else have this issue with Fedora livecds or usb keys?
I think my next best option is to make use of aufs, hopefully without needing to write a dracut module or hook.