磨損均衡在提高SSD使用壽命中的應(yīng)用與改進
發(fā)布時間：2018-08-19 12:09
【摘要】：固態(tài)硬盤是當下存儲界很熱的一個詞,在存儲界的同仁都清楚,未來的存儲硬盤將由現(xiàn)在的機械硬盤轉(zhuǎn)到固態(tài)硬盤上面。從最開始的20MB的容量到現(xiàn)在幾TB的容量,固態(tài)硬盤正在發(fā)生著翻天覆地的變化.每一年都有新的產(chǎn)品的推出,未來PCIE固態(tài)硬盤的出現(xiàn),讀寫數(shù)據(jù)的速度將會是一個幾何級的增長.固態(tài)硬盤(Solid State Drive)是一種非易失性的存儲設(shè)備,可以長時間在固態(tài)閃存介質(zhì)中的存儲數(shù)據(jù)。固態(tài)硬盤實際上沒有像傳統(tǒng)硬盤那樣有很多固定的機械形式,例如沒有機械硬盤那樣的磁頭和磁盤。換句話說,固態(tài)硬盤只是一組半導(dǎo)體存儲陣列的組織的硬盤,存儲介質(zhì)使用的是集成電路一樣的NAND性介質(zhì),而不是磁性介質(zhì)。由于固態(tài)硬盤有更高的讀寫性能,所以導(dǎo)致開發(fā)和采用固態(tài)硬盤的方案達到了快速擴張的需求。另外固態(tài)硬盤在隨機讀寫訪問數(shù)據(jù)方面比傳統(tǒng)硬盤的響應(yīng)延時要小很多,這樣固態(tài)硬盤對于大規(guī)模的讀或者隨機訪問的工作量有著巨大的優(yōu)勢。這種低延時的特性就是因為固態(tài)硬盤可以直接有能力從閃存NAND中直接立刻的讀取出數(shù)據(jù)來。但是如果讀寫擦除的數(shù)據(jù)總是坐落于NAND閃存介質(zhì)中的某一特殊塊中,這樣這一特殊數(shù)據(jù)塊將會比其他所有的NAND數(shù)據(jù)塊很快磨損壞掉,這樣將會過早的導(dǎo)致整個固態(tài)硬盤的使用壽命的結(jié)束。出于這個原因的考慮,固態(tài)硬盤的控制器,也是本篇論文重點地陳述觀點,將會使用一種稱之為磨損均衡的技術(shù),將寫和擦除盡可能的將所寫的數(shù)據(jù)均勻的分布在所有的SSDNAND存儲介質(zhì)的每個數(shù)據(jù)塊中。對于這個完美的場景的實現(xiàn),將會使每一個NAND存儲數(shù)據(jù)的塊達到最大的生命周期,然后會在某一時刻同時壞掉,以達到最大的固態(tài)硬盤使用周期。但是不幸的是,這一過程存在著很多不可定得因素,包括一些經(jīng)常使用讀寫的數(shù)據(jù)我們稱之謂熱數(shù)據(jù),和一些很少被讀寫到的數(shù)據(jù)稱之為冷數(shù)據(jù)。冷數(shù)據(jù)和熱數(shù)據(jù)將導(dǎo)致存儲在的NAND介質(zhì)數(shù)據(jù)塊的讀寫擦除計數(shù)將會嚴重不平衡,這就促使找到一個關(guān)鍵的算法解決或者緩和這種問題。磨損均衡算法正是在這種情況下面提出來優(yōu)化改進NAND存儲數(shù)據(jù)塊的讀寫擦除計數(shù)生成的.但是磨損均衡算法也會相應(yīng)的帶來一些不必要的寫放大損耗,于是本文創(chuàng)新的雙池磨損均衡算法可以使優(yōu)化性能與損耗性能達到一個平衡點,使固態(tài)硬盤相對達到一個最大的使用壽命,而性能相對沒有明顯的降低。
[Abstract]:Solid state drives are a hot term in storage, and everyone in the storage world knows that future storage drives will be switched from mechanical drives to solid state drives. From the beginning of the 20MB capacity to the current several terabytes of capacity, solid-state drives are changing dramatically. Every year there are new products coming out, and the future of PCIE solid-state drives, the speed of reading and writing data will be a geometric growth. Solid-state hard disk (Solid State Drive) is a non-volatile storage device that can store data in solid-state flash media for a long time. Solid state drives do not actually have the same fixed mechanical forms as traditional hard drives, such as magnetic heads and disks without mechanical hard drives. In other words, the solid-state disk is just a set of semiconductor memory arrays of the organization of the hard disk, storage media using integrated circuit like the NAND medium, rather than magnetic media. Due to the higher read and write performance of solid state hard disk, the development and adoption of solid state hard disk scheme meet the requirement of rapid expansion. In addition the random read and write access data in the solid-state disk is much smaller than the traditional hard disk response delay so the solid-state disk for large-scale read or random access workload has a huge advantage. This low latency feature is due to the ability of solid-state drives to read data directly from flash NAND. But if the read and write erasure data is always in a particular block in the NAND flash media, this particular block will wear out faster than any other NAND data block. This will prematurely lead to the end of the life of the entire solid-state disk. For this reason, the solid-state hard disk controller, which is also the focus of this paper, will use a technique called wear equalization. Write and erase the data evenly distributed as much as possible in each block of all SSDNAND storage media. The implementation of this perfect scenario would allow each block of NAND to store data for the maximum life cycle, and then break down at some point at the same time to achieve the maximum lifetime of the solid-state disk. Unfortunately, there are many uncertainties in this process, including some data that is often read and write, which we call hot data, and some data that is rarely read or written, called cold data. Cold data and hot data will lead to a serious imbalance in the read and write erasure count of stored NAND data blocks, which leads to finding a key algorithm to solve or alleviate this problem. It is in this case that the wear equalization algorithm is proposed to optimize the generation of read and write erasure counting for NAND storage data blocks. However, the wear equalization algorithm will also bring some unnecessary write amplification losses, so the novel two-cell wear equalization algorithm can achieve a balance between the optimal performance and the loss performance. Make solid-state hard disk relatively reach a maximum service life, but the performance is relatively not significantly reduced.
【學(xué)位授予單位】：華東理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TP333.35
本文編號：2191610
[Abstract]:Solid state drives are a hot term in storage, and everyone in the storage world knows that future storage drives will be switched from mechanical drives to solid state drives. From the beginning of the 20MB capacity to the current several terabytes of capacity, solid-state drives are changing dramatically. Every year there are new products coming out, and the future of PCIE solid-state drives, the speed of reading and writing data will be a geometric growth. Solid-state hard disk (Solid State Drive) is a non-volatile storage device that can store data in solid-state flash media for a long time. Solid state drives do not actually have the same fixed mechanical forms as traditional hard drives, such as magnetic heads and disks without mechanical hard drives. In other words, the solid-state disk is just a set of semiconductor memory arrays of the organization of the hard disk, storage media using integrated circuit like the NAND medium, rather than magnetic media. Due to the higher read and write performance of solid state hard disk, the development and adoption of solid state hard disk scheme meet the requirement of rapid expansion. In addition the random read and write access data in the solid-state disk is much smaller than the traditional hard disk response delay so the solid-state disk for large-scale read or random access workload has a huge advantage. This low latency feature is due to the ability of solid-state drives to read data directly from flash NAND. But if the read and write erasure data is always in a particular block in the NAND flash media, this particular block will wear out faster than any other NAND data block. This will prematurely lead to the end of the life of the entire solid-state disk. For this reason, the solid-state hard disk controller, which is also the focus of this paper, will use a technique called wear equalization. Write and erase the data evenly distributed as much as possible in each block of all SSDNAND storage media. The implementation of this perfect scenario would allow each block of NAND to store data for the maximum life cycle, and then break down at some point at the same time to achieve the maximum lifetime of the solid-state disk. Unfortunately, there are many uncertainties in this process, including some data that is often read and write, which we call hot data, and some data that is rarely read or written, called cold data. Cold data and hot data will lead to a serious imbalance in the read and write erasure count of stored NAND data blocks, which leads to finding a key algorithm to solve or alleviate this problem. It is in this case that the wear equalization algorithm is proposed to optimize the generation of read and write erasure counting for NAND storage data blocks. However, the wear equalization algorithm will also bring some unnecessary write amplification losses, so the novel two-cell wear equalization algorithm can achieve a balance between the optimal performance and the loss performance. Make solid-state hard disk relatively reach a maximum service life, but the performance is relatively not significantly reduced.
【學(xué)位授予單位】：華東理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TP333.35
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