快閃記憶體相較於傳統硬碟，具有存取速度高、抗震防摔、功耗低、體積小等優勢，隨著製程的不斷發展，成本有著明顯的降低，在此趨勢下以快閃記憶體為儲存介質的固態硬碟，逐步成為主流市場上的新寵。然而快閃記憶體有許多先天上的限制。例如:資料寫入跟擦除的基本單位不對稱、無法直接覆寫及記憶體有總寫入上限等。在這些快閃記憶體的先天限制下，為了要模擬傳統硬碟，固態硬碟藉由FTL(快閃記憶體轉換層)，來管理底層複雜的快閃記憶體操作。而為了要讓熱資料的存取更有效率，及降低對快閃記憶體產生多餘的寫入操作，以延長快閃記憶體的使用壽命，在檔案系統與快閃記憶體之間通常會加上DRAM作為快取，用來吸收大量的資料更新。然而快取有其容量限制，當快取空間已滿卻又需放入新的資料時，如何選擇合適的Page移出是過去經常研究的方向，同時也是本篇論文想探討的議題。本篇論文提出的快取管理機制，試圖透過分析Request彼此間的關聯性，將具有強關聯性的Request定義為重要資料，並於快取內將這些重要資料加以保存，藉此提高快取命中率，根據實驗結果顯示，我們提出的方法與既有的快取管理機制LRU、ARC相比，快取命中率分別平均提升約34.74%、18.18%。

Compared with traditional hard drives, flash memory has the advantages of fast- access speed, shock resistance resistance, low-power consumption, and small size. With the continuous development of the manufacturing process, the cost has been significantly reduced. In this trend, the flash memory chip-based solid-state hard-disk with has gradually become the new favorite in the mainstream market. However, flash memory has many inherent limitations, such as the basic unit of data writing, and erasing is asymmetrical, cannot be overwritten directly, and the memory has a total writing upper limit. Under the inherent limitations of these flash memories, in order to simulate traditional hard drives, solid state drives use FTL (Flash Memory Translation Layer) to manage the underlying complex flash memory operations. To make the hot data-access more efficient, and reduce redundant write operations to the flash memory, thereby extending the service life of the flash memory, DRAM is used as a cache to absorb a large amount of data updates from the file system. The cache management mechanism proposed in this paper attempts to analyze the association of Requests and define requests with the strong association as important data, and save these important data in the cache to improve cache hit ratio. According to the experimental results, compared with the existing cache management mechanisms LRU and ARC, the cache hit ratio of our proposed method is increased by about 34.74% and 18.18% respectively.

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