I've installed a DVD writer on my Gentoo system and it works great for files/dirs under 4.7GB. I love it. I'm using growisofs. The problem is, I don't know how write files to the DVD drive that are greater than 4.7GB. Is there a program that will break up a very large file (something that I've tarred and zipped) into chunks that are less than 4.7GB?

If not, what suggestions do you have?

The largest directory I need to backup is somethinng like 44GB. I can tar this and then zip it so that it will be less than 44GB, but it will still be way too big to put on one DVD. Thanks!

Check out 'man split', it might be of some use.
Joining them would be a whole other matter... You would probably have to copy all the pieces to your hdd then use cp to rejoin them.
You might want to search freshmeat or google maybe for a backup program that will help you do what you want, instead of trying to split up a tarball and burning them to dvds.
When I do a backup I normally just copy as much as I can to a dvd, then repeat, somehow remembering what I've already burnt as I go along, instead of tarballing it.

Just a few ideas.

If you use split the divide the file into smaller files you can use cat to put them back together when needed.

Keep in mind that the large file will need to be recreated to access it. By dividing your folders up into seperate files you may be able to insert a dvd and restore files without the hassle or the available space and time.

Thanks so much guys! I'll give it a try. I very much appreciate it!