近年來非揮發性隨機存取記憶體(NVRAM)科技已經有長足的進展。這些NVRAM有比快閃記憶體更好的性能。但是現在NVRAM的價格依舊高而容量卻很小，所以之前的研究著重在使用NVRAM儲存檔案系統的metadata來加強效能。然而，在之前的研究中，NVRAM的容量限制了檔案系統metadata的大小。所以我們提出了一個混合式儲存系統，TridentFS，來解除這項限制。TridentFS結合了NVRAM，硬碟與固態磁碟。本篇論文著重在管理TridentFS的NVRAM部分，並同時考量擴展性，效能，以及使用NVRAM空間的效率等要求。我們用NVRAM來儲存頻繁使用的metadata，剩餘的資料則被移出NVRAM，儲存在固態硬碟或是硬碟上。實驗結果顯示當檔案集合全部在NVRAM上時，TridentFS比在ext4檔案系統在RAM Disk上快3倍，比ext4在固態硬碟上快91倍，顯示了我們的NVRAM管理方法的效率。

Non-Volatile RAM (NVRAM) technology has rapid development in recent years. NVRAMs have better performance than flash memory. However, they currently have higher prices and lower densities. Therefore, previous researchers only utilized NVRAM to store the metadata of the storage systems. This limits the size of the metadata of the storage systems. To address this problem, we proposed a hybrid storage system called TridentFS, which combines the NVRAM, hard disk and Solid State Disk (SSD). This thesis focuses on the management of the NVRAM in TridentFS, which considers the issue of scalability, performance, and efficient use of the NVRAM space. In TridentFS, NVRAM is used to keep frequently-accessed metadata, and the remaining data are evicted from NVRAM and stored in the SSD or disk. The experiment results show that TridentFS outperforms the ext4-on-ramdisk implementation and the ext4-on-SSD implementation by 3 and 91 times, respectively, when file set fits in the NVRAM space, demonstrating the effectiveness of our NVRAM management approach.

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