本文選題：閃存 + 固態(tài)硬盤�。� 參考：《國防科學(xué)技術(shù)大學(xué)》2012年碩士論文

【摘要】：由于閃存獨(dú)特物理特性的限制，閃存存儲塊的擦除次數(shù)不能超過一個上限，否則存儲在里面的數(shù)據(jù)就會不可靠。因此需要采用損耗均衡算法將固態(tài)硬盤的磨損均衡到整個存儲空間中，從而延長固態(tài)硬盤的使用壽命。但是損耗均衡算法會引入額外的擦寫操作，并且隨著大容量閃存最大可擦除次數(shù)的降低，損耗均衡算法所引入的額外擦除次數(shù)帶來的影響逐漸突顯出來。本文為解決大容量固態(tài)硬盤控制器中損耗均衡算法引入額外擦除次數(shù)較多的問題展開研究，主要做了以下幾方面的工作： （1）介紹了閃存及固態(tài)硬盤的特點(diǎn)和損耗均衡算法在閃存存儲系統(tǒng)中的重要作用，分析了目前損耗均衡算法的研究現(xiàn)狀，指出了損耗均衡研究的熱點(diǎn)和未來發(fā)展趨勢，并通過分析對比選擇了混合損耗均衡算法進(jìn)行改進(jìn)。 （2）針對混合損耗均衡算法額外擦除次數(shù)較多的問題，提出了一種區(qū)分組內(nèi)組間策略的改進(jìn)方法，將資源消耗小的隨機(jī)性損耗均衡策略應(yīng)用于分組內(nèi)部，將均衡效果好的確定性損耗均衡策略應(yīng)用于分組之間。在組內(nèi)，通過控制組內(nèi)隨機(jī)性損耗均衡的觸發(fā)頻率和提高冷數(shù)據(jù)選擇的精度降低了混合損耗均衡算法組內(nèi)損耗均衡操作帶來的額外擦除次數(shù)。組間采用閾值控制損耗均衡策略，提高了組間損耗均衡操作的針對性，，降低了混合損耗均衡算法組間損耗均衡操作帶來的額外擦除操作。提出的改進(jìn)算法利用固態(tài)硬盤并行總線這種特殊結(jié)構(gòu)，進(jìn)一步降低了混合損耗均衡算法所需要的內(nèi)存空間。 （3）設(shè)計了一系列的仿真和測試實(shí)驗(yàn)，對提出的改進(jìn)混合損耗均衡算法的均衡效果、額外擦除比例、內(nèi)存消耗和處理器資源消耗等性能進(jìn)行了仿真測試，仿真和測試結(jié)果表明提出的改進(jìn)算法能夠保持損耗均衡的效果和所需的內(nèi)存開銷基本不變，同時將額外擦除比例從1.7降低到1.2。
[Abstract]:Due to the limitations of the unique physical characteristics of flash memory, the number of erasures of flash memory blocks cannot exceed one upper limit, otherwise the data stored in it will be unreliable. Therefore, it is necessary to use loss equalization algorithm to equalize the wear of solid state hard disk to the whole storage space, so as to prolong the service life of solid state hard disk. However, the loss equalization algorithm will introduce additional erasure operations, and with the reduction of the maximum erasable number of large capacity flash memory, the influence of the additional erasure times introduced by the loss equalization algorithm is gradually becoming more and more obvious. In order to solve the problem of introducing more extra erasure times into the loss equalization algorithm of solid state hard disk controller with large capacity, this paper mainly does the following work: This paper introduces the characteristics of flash memory and solid state hard disk and the important role of loss equalization algorithm in flash memory system, analyzes the present research status of loss equalization algorithm, and points out the research hotspot and future development trend of loss equalization. The hybrid loss equalization algorithm is improved by analyzing and comparing. 2) aiming at the problem of more erasure times in hybrid loss equalization algorithm, an improved method to distinguish the inter-group strategy is proposed, which applies the random loss equalization strategy with low resource consumption to the intra-group. The deterministic loss equalization strategy with good equalization effect is applied between groups. In the group, by controlling the trigger frequency of random loss equalization in the group and improving the precision of cold data selection, the extra erasing times of the hybrid loss equalization algorithm are reduced. The threshold control loss equalization strategy is adopted among the groups, which improves the pertinence of the inter-group loss equalization operation and reduces the additional erasure operation caused by the hybrid loss equalization algorithm. The improved algorithm further reduces the memory space required by the hybrid loss equalization algorithm by utilizing the special structure of the parallel bus of the solid-state hard disk. A series of simulation and test experiments are designed to test the performance of the improved hybrid loss equalization algorithm, such as equalization effect, extra erasure ratio, memory consumption and processor resource consumption. The simulation and test results show that the proposed algorithm can keep the loss equalization effect and memory overhead unchanged, and reduce the extra erasure ratio from 1.7 to 1.2.
【學(xué)位授予單位】：國防科學(xué)技術(shù)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2012
【分類號】：TP333

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