To be pedantic, I think you need to say "the act of writing to a hard drive adds mass". There is no reason to expect that writing a 1 or a 0 adds more or less m

To be pedantic, I think you need to say "the act of writing to a hard drive adds mass". There is no reason to expect that writing a 1 or a 0 adds more or less mass; if there is a difference in energy states, it would depend on the encoding scheme.