Problems splitting rar files

hey when i try using the rar program to split my rar files into 3 different parts, cause i have a 9.17 gb folder i wanna backup onto DVDs. i tried doing the "split to vollumes, bytes" thing and when i put in the desired 3gb i wanna split the files into 3 part rar files it doesn't work properly just goes into the one file. it works when i do a few bytes, or kbss, or mbs but any more than maybe a few 100 mbs it doesn't work. can anyone help me to split my files into 3 parts and figure how to do rar ssplitting properly please
 
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