3.3 and 3.4 file servers should interoperate perfectly well. You
should not run 3.3 and 3.4 {pt,vl,ka,bu} servers together for any length
of time, but you needn't go to heroic efforts to avoid doing so. If you
upgrade all your database servers of the same type at a single sitting,
you'll be fine. You should be able to manage the upgrade without
causing an interruption in service; we went to some effort to ensure
that would be possible.
As a general rule, you should not upgrade any file servers to 3.4 until
all your vlservers have been upgraded to 3.4.
Read the documentation. I think it's pretty clear. The GA docs should
be a little more accurate than the beta docs, if you can wait for them.
If you prefer not to read the instructions and want to play
fast-and-loose, and can tolerate a brief interruption of service, well,
you probably won't permanently break anything, as long as you note the
general rule above.
