Non-Volatile Main Memories (NVMMs) have recently emerged as a promising technology for future memory systems. Generally, NVMMs have many desirable properties such as high density, byte-addressability, non-volatility, low cost, and energy efficiency, at the expense of high write latency, high write power consumption, and limited write endurance. NVMMs have become a competitive alternative of Dynamic Random Access Memory (DRAM), and will fundamentally change the landscape of memory systems. They bring many research opportunities as well as challenges on system architectural designs, memory management in operating systems (OSes), and programming models for hybrid memory systems. In this article, we first revisit the landscape of emerging NVMM technologies, and then survey the state-of-the-art studies of NVMM technologies. We classify those studies with a taxonomy according to different dimensions such as memory architectures, data persistence, performance improvement, energy saving, and wear leveling. Second, to demonstrate the best practices in building NVMM systems, we introduce our recent work of hybrid memory system designs from the dimensions of architectures, systems, and applications. At last, we present our vision of future research directions of NVMMs and shed some light on design challenges and opportunities.

非易失性主存储器（NVMM）最近已成为未来存储系统的有希望的技术。通常，NVMM具有许多合乎需要的属性，例如高密度，字节寻址能力，非易失性，低成本和能效，但代价是高写入延迟，高写入功耗和有限的写入耐久性。NVMM已成为动态随机存取存储器（DRAM）的竞争替代品，并将从根本上改变存储系统的格局。它们带来了许多研究机会，也给系统架构设计，操作系统（OSes）中的内存管理以及混合内存系统的编程模型带来了挑战。在本文中，我们首先回顾了新兴的NVMM技术的概况，然后调查了NVMM技术的最新研究。我们根据不同的维度（例如内存体系结构，数据持久性，性能改进，节能和耗损均衡）对这些研究进行分类。其次，为了演示构建NVMM系统的最佳实践，我们从体系结构，系统和应用程序的角度介绍了混合存储系统设计的最新工作。最后，我们介绍了我们对NVMM未来研究方向的看法，并阐明了设计挑战和机遇。