UnionFS needs to be ported to Dracut. Reproducible: Always
Please note there is a variety of "UnionFS" around. I'll just paste a quick summary made for a friend earlier here. sys-fs/unionfs-fuse - http://podgorny.cz/moin/UnionFsFuse - FUSE - Gentoo main tree - (used by genkernel) - (what I use at home) sys-fs/funionfs - http://funionfs.apiou.org/ - FUSE - sunrise overlay sys-fs/unionfs - http://www.fsl.cs.sunysb.edu/project-unionfs.html - Kernel module - 1.x - Gentoo main tree - 2.x - not yet packaged sys-fs/aufs2 - http://aufs.sourceforge.net - Kernel module - Gentoo main tree
Would be awesome if dracut would support rootfs on aufs3, so I could create a rw overlay over my regular ro NFS rootfs.
When I will have more time, I will take different approach for integration Dracut with Genkernel.