Locally Rewritable Codes for Resistive Memories

Abstract

Resistive memories, such as phase change memories and resistive random access memories, have attracted significant research interest because of their scalability, non-volatility, fast speed, and rewritability. However, their write endurance needs to be improved substantially for large-scale deployment of resistive memories. In addition, their write power consumption is much higher than the power consumption of read operation. Inspired by locally repairable codes (LRCs) recently introduced for distributed storage systems, we propose locally rewritable codes (LWCs) for resistive memories. We define a novel parameter of rewriting locality , which can be connected to repair locality of LRC. As small values of repair locality of LRC enable fast repair in distributed storage systems, small values of rewriting locality of LWC are able to reduce the problems of write endurance and write power consumption. We show how a small value of rewriting locality can improve write endurance and power consumption by deriving the upper bounds on writing cost. Also, we point out the dual relation of LRC and LWC, which indicates that the existing construction methods of LRC can be applied to construct LWC. Finally, we investigate the construction of LWC with error correcting capability for random errors.