saving directories when they don't fit on 1 tape

[Bill Smith]

Is there an automatic, reasonably portable way to save a directory and all 
files beneath it on tape when it does not fit on a single piece of media 
and can not easily be split at the next level down in the directory tree?

I would like something like the multi-volume versions of tar that I have
seen (on Ultrix for example) in a Sun environment.   dump is the closest
thing I've seen, but as I understand the man page, it only works on complete
filesystems which is 2 or 3 times more data than I want to save.

Bill Smith
uunet!pur-ee!mdbs!wsmith