Great post. You might be able to elide the RAM disk in lieu of the "mbuffer" command. My script uses a combination of dd | pv | mbuffer | mt. I omitted the options because I don't remember any of them. I personally use dd of an ext4 filesystem-on-file that is exactly the size of what will fit on tape. This was simply because I couldn't figure out how to reliably advance the tape head or how to continue a write from one tape to another.