Hard disk space for writing discs

[rock1]

is it necessary to have as much free space on hard disk while burning the data of having the size equal or more than the hard disk space with nero? nero is giving a non critical error.

for. e.g. i don't have 8.5 gb free space in any of my partition. i have 4.5 gb free space in my drive nero caches files before burning. i'm trying to burn a dual layer dvd.