Originally Posted by Euler2
I am currently trying to copy a directory of roughly 400GBs to dvd ...
Why? I would be surprised if using DVDs is the best option compared with the alternatives when cost, time (personal and system), machine load, reliability and re-usability are considered.
DVDs are great for video where a few missing blocks don't matter. At one time DVDs were so much cheaper than the alternatives that the shortcomings were outweighed by price; that no longer applies.
dar is a great program but not intuitive and does not write to DVD directly so it's a two stage process of writing to disk first and then copying to DVD (and ideally a third stage of verifying that what's on DVD matches what's on disk).
When using DVDs as backup media it is strongly recommended that error detection and correction data is also written. par2 is a good utility for that. The CPU and disk IO to create such data is significant, say 30 mins per 4 GB.