Saving Bit-flips through Smart Overwrites in NVRAM

New generations of non-volatile random access memories will combine the best features memory (access times, byte addressability) with storage (non-volatility, low costs per byte). Some, like PCM, have a limited endurance. All only consume energy when accessed, but writes use much more than reads. These characteristics put cost on flipping bits in memory. Bit-flip aware data structures lower number flipped by not resetting fields to zero indicate deleted record using bit-maps. If given choice where over-write data, they select location which results bit-flips. We calculate expected bit-flip savings this strategy and derive rule determine possible candidate locations.