Step-by-Step Design of memory hierarchy for heterogeneously-integrated SCM/NAND flash storage

摘要

This paper presents the Step-by-Step Design of memory hierarchy for heterogeneously-integrated SCM/NAND flash storage. The heterogeneously-integrated storages utilize multiple types of non-volatile memories such as storage class memories (SCMs) and NAND flash memories. SCMs are further classified to memory-type and storage-type. NAND flash memories are also characterized by the number of stored bits per cell. These non-volatile memories show complex trade-off of various latency, power, capacity and cost. What's worse, in NAND flash, garbage collection seriously degrades the performance. Thus, the intelligent mix & match of these memories is required, depending on each workload. For various storage applications, this paper shows that optimal SCM/NAND flash hierarchies are determined by considering system performance, energy consumption, endurance, and cost for each workload. The recommended non-volatile memory combinations with SCMs and NAND flash memories are proposed for representative 7 storage application workloads with diverse characteristics. The proposed Step-by-Step Design is the useful solution for the heterogeneously-integrated storage with multiple types of non-volatile memories and for various applications.