Wouldn't RNA be the RAM and DNA be long term storage? Most of the work and "decision making" - at least in current organisms - is done by proteins.
DNA is environmentally sensitive and it can be altered. Your entire genome is not being produced all the time. Different proteins are copied based upon the conformal structure of DNA which changes based upon the cellular environment. The entire structure is copied often and no one particular set of DNA in your body is "the original."
It has aspects of long term storage but then it's utilized in a way that long term storage almost never is. And all cells get their own copy which may be unique in several ways. So RAM seems like a better metaphor to me.
[1]: https://en.wikipedia.org/wiki/Neutrophil_extracellular_traps