[Unionfs] WTF!? UnionFS, aufs and mhddfs !?.

[Erez Zadok]

Serge, first, you're going to be disappointed because there are even more
unioning-like projects: several past and ongoing Union Mount efforts (see
recent lkml postings from Val, for example).  Worse, there have been over
the years several more suggestions, including hacking lower file systems
such ext2 and/or tmpfs to support a 2-branch union directly.  There are
multiple projects partly because, historically, different groups wanted a
different set of features, and several groups had different opinions which
is the "best" design/implementation for it.

The best advise I can give you is to try a few of those, find what works for
you, and stick with it.

Erez.