## 3 Performance Implication of NVM Based Storage
### Implications of Alternative PC Configurations  
Based on the aforementioned experimental results, this section presents an alternative PC configuration by adopting NVM storage, and discusses the effectiveness of such configurations with respect to the cost, lifespan, and power consumption. Due to the recent advances in multi-core and many-core processor technologies, new types of applications such as interactive rendering and machine learning are also performed in desktop PCs. This is in line with the emerging era of the Fourth Industrial Revolution as well as the recent trend like personalized YouTube broadcasting, where creating high  
Figure 11: Performance comparison of HDD, RAMDisk, and PCMdisk varying the number of threads. quality contents or performing computing-intensive jobs is no longer the domain of the expert. Thus, the performance of desktop systems should be improved in accordance with such situations. While the processor's computing power has improved significantly, it is difficult to increase the memory capacity of desktop PCs due to the scaling limitation of DRAM. Thus, instead of increasing the memory capacity, we argue that NVM storage can provide an alternative solution to supplement the limited DRAM size in emerging applications. That is, a future computer system can be composed of limited memory capacities but has NVM storage devices, not to degrade performances. Figure 12 shows the architecture of an alternative PC consisting of small DRAM and fast NVM storage in comparison with a traditional PC consisting of large DRAM and slow HDD. Table 2 lists the detailed specifications and estimates of a \"large DRAM and slow HDD PC\" (hereinafter we will refer to it as \"HDD PC\") and a \"small DRAM and fast NVM PC\" (hereinafter we will refer to it as \"NVM PC\"). By considering emerging desktop workloads such as interactive rendering, big data processing, and PC virtualization, we use a large memory of 64 GB in HDD PC. In contrast, we use the memory size of 16 GB in NVM PC based on the observations in Section 3.1. For NVM storage, we use Intel's Optane SSD, which is the representative NVM product on the market at this time [27]. As shown in Table 2, the total price of NVM PC is similar to that of HDD PC. This is because not only the memory itself but also the mainboard becomes expensive when the memory capacity is very large. A more serious problem is that the memory size is difficult to be extended any longer due to the scaling limitation of DRAM. When the market of NVM storage fully opens, it can be anticipated that the price of NVM will become more competitive. Even though an auxiliary HDD is added to NVM PC, it will not significantly affect the total price. Now, let us discuss the lifespan issue of NVM. The technical specifications of Optane 900p indicate that the endurance rating is 8.76 PBW (peta bytes written), which implies that we can write 8.76 PB into this device before we need to replace it. As its warranty period is specified to be 5 years, if we evaluate the average amount of daily writing allowed, it is 8.76 PB/(5 years \(\times\) 365 days/year) = 4.9152 TB per day. As the size of the Optane 900p product is 280 GB or 480 GB, this implies that writing more than 10 times to the full storage capacity every day is allowed for 5 years. When we compare it with flash-based SSDs, we do not need to consider the endurance problem in NVM storage devices. Figure 12: An alternative PC consisting of small DRAM and fast NVM storage in comparison with the traditional PC consisting of large DRAM and slow HDD. Now, let us consider the power issue. We analyze the power consumptions of memory and storage separately and then accumulate them.