At 12 hours of labor per day, that's roughly one per minute. So, at minimum you need one machine more than the number of minutes it takes each machine to rip t

At 12 hours of labor per day, that's roughly one per minute. So, at minimum you need one machine more than the number of minutes it takes each machine to rip the DVD. If you also have to burn a second set of DVDs, you will need at least one machine more than the number of minutes it takes to burn a DVD plus the aforementioned ripping machines. If you're just storing the DVD images after ripping, that part can be at least partly automated, set up a machine as a central server (about 20 terabytes should do it if nothing goes wrong) and have each 'ripper' run a script to copy the image up after the rip is done (which hopefully it can do while also starting the next rip, if not you'll even need more machines).