onbar

I have 2 instances I need to back up through onbar, and I'm wondering how many tape drives I need. They are both very small, about 1GB a piece, and should easily fit on the 4 GB dat drive I have. Of course I'm going to want the logs backed up too. I'm using onbar so that the whole thing is automated. How many tape drives do I need? Is onbar smart enough to be able to put system backups and logs on the same tape? If so, I could easily get by with 2 tape drives and possibly one. If not, I'll need at least 4 to avoid having to swap tapes daily. At that point, a juke box might be the way to go. Any suggestions?