近年來，快閃記憶體的容量成長快速，固態硬碟在市場上變成非常流行。固態硬碟內部使用的NAND 型快閃記憶體，需要一個中介層稱為快閃記憶體轉換層，來隱藏快閃記憶體本身的特性，並且對快閃記憶體進行管理，因此，快閃記憶體轉換層需要處理不同資料存取的特性。當固態硬碟採用軟體定義的快閃記憶體轉換層，使用者可以在固態硬碟內部選擇不同的快閃記憶體轉換層，本篇論文將提出快閃記憶體轉換層的轉換，來改善SSD的效能。我們解決一些問題如空間管理、資料讀/寫及垃圾回收。實驗結果顯示本論文所提出的方法對於不同的I/O 存取模式有好的效能表現。

Because the capacity of NAND flash memory has increased rapidly, a solid-state drive (SSD) that adopts NAND flash memory has become popular in the market. In particular, an intermediate software called a flash translation layer (FTL) is adopted to hide the characteristics of NAND flash memory and provide efficient management for NAND flash memory. Therefore, an SSD needs a flash translation layer to handle different I/O access patterns. When a software-defined flash translation layer is adopted for users to select different flash translation layers inside an SSD, we will propose transformation of flash translation layers to improve SSD performance in the thesis. We will solve some issues such as space management, data reads/writes, and garbage collection during the transformation. The experimental results show that the proposed method could achieve a good performance for various I/O access patterns.

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