My immediate thought was of a roan horse, since roan is a type of coloring for a horse or other animal (the base color is intermixed with white hairs). I don't know how commonly known that word is, but it's something to keep in mind.
Personally I don't care for the sound of it as a name, and it sounds very bland and forgettable to me. I think the spelling Roan looks better if you're going to use it.
You might also consider some similar sounding names, such as
Ronan,
Rowan, and
Rune.