growisofs ejects when finished

[Jeffrey Barish <jeffbarish@starband.net>]

I am using growisofs to backup to DVD.  Whenever growisofs finishes
writing, it ejects the DVD.  At that point, the DVD is obviously no
longer mounted.  I would like for the DVD to remain mounted  so that
subsequent backups don't cost one mount (since, as I recall, each mount
counts as a write).  Is there a way to do that with growisofs?  Should
I use another program instead to write to DVD?  (I'm using DVD+RW, but
my drive supports DVD-RW also.)
-- 
Jeffrey Barish