Acronis do not pay attention to my user entered splitting size

Hello
I would like to ask you if you know why when I entered 100 GB as customized splitting size in the options tabs for a scheduled task, it did not do it like that but by using the default 4194304 KB size of DVD and creating too many files of this size. I was trying to back up 50 GB of data and did not want so many files but just one. I guess I have no need to create DVDs because I do not plan to burn 50GB to more than ten DVDs unless you tell me that there is any advantage in doing so against having just one huge backup file in a external hard disk as I planned from the beginning.

Does any of you what to do to solve this?

Thanks