本文選題：SSD + RAID5控制器　； 參考：《國防科學(xué)技術(shù)大學(xué)》2013年碩士論文

【摘要】：隨著數(shù)字設(shè)備的普及和網(wǎng)絡(luò)的飛速發(fā)展,當(dāng)今世界已經(jīng)成為數(shù)據(jù)的世界,數(shù)據(jù)存儲系統(tǒng)面臨著極大的挑戰(zhàn)。當(dāng)前應(yīng)用不僅需要更大的存儲容量,在延遲、帶寬、可靠性、能耗等方面也對存儲系統(tǒng)提出了更高的要求。傳統(tǒng)磁盤設(shè)備因其內(nèi)部機械裝置的限制,已經(jīng)成為大規(guī)模存儲系統(tǒng)的主要性能瓶頸�；陂W存的SSD(Solid State Drive)以其優(yōu)異的性能、非易失和低功耗等特點,已經(jīng)在高端系統(tǒng)中得到廣泛的應(yīng)用。但是,閃存存在壽命有限的缺陷,當(dāng)閃存應(yīng)用到大規(guī)模存儲系統(tǒng)中時存在可靠性方面的問題。RAID(Redundant Arrays of Independent Disks)是一種傳統(tǒng)的提高存儲可靠性的方案。利用RAID技術(shù)構(gòu)建大規(guī)模閃存陣列,既可以增大閃存存儲系統(tǒng)的容量,提高性能,又能保證可靠性。本文重點研究基于RAID5的SSD陣列,根據(jù)RAID的特性優(yōu)化了SSD的內(nèi)部結(jié)構(gòu),并根據(jù)閃存的特性改進了RAID5的控制邏輯,通過兩者的結(jié)合延長RAID5陣列中SSD的壽命。文章的主要工作和創(chuàng)新點如下:首先,針對閃存壽命有限的問題,提出了一種能夠感知RAID5校驗信息的PA-SSD(Parity Aware-SSD)結(jié)構(gòu),該結(jié)構(gòu)在SSD內(nèi)部合理布局RAID5產(chǎn)生的校驗信息,減少SSD內(nèi)部產(chǎn)生的額外寫請求,從而延長SSD的壽命。另外,該結(jié)構(gòu)在SSD控制器內(nèi)部提出了基于權(quán)重值的寫緩存替換策略,并優(yōu)化了FTL(Flash Translation Layer)的地址映射策略和損耗均衡策略。其次,改進了RAID5控制器的內(nèi)部結(jié)構(gòu)。針對程序中數(shù)據(jù)的局部性,在RAID5控制器內(nèi)部增加寫緩存,減少寫入SSD的數(shù)據(jù)量;針對校驗信息更新頻繁的問題,設(shè)置數(shù)據(jù)緩存和部分校驗緩存,分別接收從寫緩存替換出的用戶數(shù)據(jù)和校驗信息,減少校驗信息更新時產(chǎn)生的I/O請求,延長SSD的壽命。最后,實現(xiàn)了基于RAID5的SSD陣列模擬器,并基于該模擬器評估了本文提出的PA-SSD結(jié)構(gòu)和改進的RAID5控制器。實驗結(jié)果表明,PA-SSD平均能夠使校驗信息的寫入量減少26%,閃存芯片的擦除次數(shù)降低17%,閃存內(nèi)部的數(shù)據(jù)遷移量降低32%。另外,改進的RAID5控制器能夠使整個陣列的寫請求數(shù)降低66%,寫延遲降低44%。
[Abstract]:With the popularity of digital devices and the rapid development of the network, the world has become a data world, data storage system is facing a great challenge. Current applications not only need larger storage capacity, but also put forward higher requirements for storage system in terms of delay, bandwidth, reliability, energy consumption and so on. Traditional disk devices have become the main performance bottleneck of large-scale storage system because of the limitation of internal mechanical devices. Flash memory based solid State driven has been widely used in high-end systems due to its excellent performance, non-volatile and low power consumption. However, flash memory has the limitation of limited lifetime. When flash memory is applied to large scale storage system, there is a reliability problem. Raid undant Arrays of Independent disks) is a traditional method to improve storage reliability. Using raid technology to construct large scale flash memory array can not only increase the capacity of flash memory system, but also improve the performance and reliability. This paper focuses on the SSD array based on RAID5, optimizes the internal structure of SSD according to the characteristics of raid, improves the control logic of RAID5 according to the characteristics of flash memory, and prolongs the life of SSD in RAID5 array by combining the two. The main work and innovations of this paper are as follows: firstly, in order to solve the problem of limited flash memory life, a PA-SSD-Parity Aware-SSD-based structure is proposed, which can sense the verification information of RAID5. Reduces additional write requests generated within the SSD, thereby prolonging the life of the SSD. In addition, the structure proposes a write-cache replacement strategy based on weight value in the SSD controller, and optimizes the address mapping strategy and loss equalization strategy of FTL / Flash Translation layer. Secondly, the internal structure of RAID5 controller is improved. Aiming at the locality of data in the program, adding write cache inside RAID5 controller, reducing the amount of data written to SSD, setting up data cache and partial check cache for frequent updating of checkout information. The user data and verification information replaced from the write cache are received respectively to reduce the I / O requests generated when the checkout information is updated and to prolong the life of SSD. Finally, the SSD array simulator based on RAID5 is implemented, based on which the PA-SSD structure and the improved RAID5 controller are evaluated. The experimental results show that PA-SSD can reduce the write amount of verification information by 26 times, erase the memory chip by 17 times, and reduce the internal data migration of flash memory by 32 parts on average. In addition, the improved RAID5 controller can reduce the number of write requests and write delay by 66% and 44% respectively.
【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】：2013
【分類號】：TP333
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本文編號：2043808