NAND型快閃記憶體已經廣泛應用在電腦以及消費性電子裝置上。其中，多階式 (MLC) NAND型快閃記憶體允許兩個或多個以上的位元儲存在ㄧ個儲存單位中，提高了資料儲存密度，也因此降低了成本。低廉的價格讓多階式NAND型快閃記憶體在消費產品或是數據中心市場上受歡迎。在一個多階式NAND型快閃記憶體中，頁讀取延遲時間會因為頁的種類而有所差異。對於讀取密集的工作量來說，如果常讀取的資料放在讀取延遲長的頁將會造成效能降低。本篇論文中提出了FastRead，對於以多階式NAND型快閃記憶體為主的儲存空間，可以即時的增進讀取效能。FastRead動態辨識讀取的資料，並將其移動到讀取延遲較短的頁中，增進了讀取效能。根據實驗結果，對於三階式NAND型快閃記憶體，FastRead最多可以減少33%的讀取時間 (平均20%)。除此之外，FastRead並不會對寫入密集的工作量帶來明顯的負面影響，而且額外開銷也很小。

NAND flash memory has been widely used in computer and consumer electronic devices. Multilevel-cell (MLC) NAND flash memory allows two or more bits to be stored per cell, improving the cell density and hence reducing the cost. The lower price of MLC NAND has made it appearing in both consumer product and datacenter markets. In MLC NAND, the page read latency varies according to the page type. For read-dominated workloads, placing read-intensive data into pages with longer read latencies may result in degraded read performance. In this thesis, an online method called FastRead is proposed to improve the read performance of MLC NAND based storage. The FastRead method dynamically identifies read-intensive data and migrates them to pages with shorter read latency to improve the read performance. According to the performance results, FastRead can reduce the read response time by up to 33% (20% on average) for read-dominated workloads on a TLC NAND. In addition, FastRead does not have noticeable performance impact for write-dominated workloads, and the overhead is insignificant.

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