Depends on where the holes are, say the side around the flange.
And the fins on the outside of the drums cause air flow, thus air current that would draw air from inside/thru/around the drum. Same as the fins in a vented rotor.
Tom
"Everyone should believe in something; I believe I'll go fishing."
-Henry David Thoreau
Men and fish are alike. They both get into trouble when they open their mouths
