本文選題：閃存　切入點：PCIe　出處：《國防科學(xué)技術(shù)大學(xué)》2012年碩士論文　論文類型：學(xué)位論文

【摘要】：信息技術(shù)的發(fā)展和普及帶來了數(shù)據(jù)的爆炸式增長，這對存儲系統(tǒng)提出了更高的要求。在過去的幾十年中，機(jī)械磁盤以其在成本和容量方面的優(yōu)勢逐漸成為傳統(tǒng)存儲系統(tǒng)中的主要存儲介質(zhì)。但是在數(shù)據(jù)存儲需求快速增長的新形勢下，傳統(tǒng)機(jī)械磁盤在讀寫延遲、能耗等方面的問題日益突出，成為了限制存儲系統(tǒng)性能提升的瓶頸。閃存作為一種新型存儲介質(zhì)，具有讀寫延遲低、非易失等特點，受到了國內(nèi)外學(xué)者和工業(yè)界人士的普遍關(guān)注�；陂W存的SSD的出現(xiàn)使得機(jī)械磁盤的瓶頸問題得到解決，隨著閃存成本的不斷降低，SSD的應(yīng)用越來越廣泛，大有取代傳統(tǒng)機(jī)械硬盤的趨勢。 本文的工作圍繞PCIe SSD設(shè)備驅(qū)動、SSD并行調(diào)度、SSD可靠性存儲系統(tǒng)等關(guān)鍵技術(shù)而展開，以應(yīng)對SSD在性能、壽命和可靠性等方面的挑戰(zhàn)性問題。本文主要完成了以下工作： 1.針對自主研發(fā)的PCIe固態(tài)存儲卡，設(shè)計實現(xiàn)了Linux操作系統(tǒng)下的驅(qū)動程序。 當(dāng)前主流的SSD大都采用了SATA等與傳統(tǒng)磁盤相同的接口，這雖然保持了與傳統(tǒng)存儲軟件體系的兼容性，也限制了SSD性能的充分發(fā)揮。基于PCIe接口的SSD能夠充分利用閃存的高并發(fā)特性，大幅提高SSD的讀寫性能，，但是由于PCIe SSD出現(xiàn)的時間尚短，業(yè)界還未形成統(tǒng)一的標(biāo)準(zhǔn)，現(xiàn)有操作系統(tǒng)的存儲驅(qū)動都是針對傳統(tǒng)磁盤設(shè)計的，對于PCIe SSD來說并不適用。本文結(jié)合自主設(shè)計的PCIe SSD，實現(xiàn)了該設(shè)備在Linux下的驅(qū)動程序。我們對傳統(tǒng)的Linux存儲架構(gòu)進(jìn)行了分析，結(jié)合PCIe SSD的硬件特性，改進(jìn)了Linux的存儲驅(qū)動模型。該驅(qū)動程序重新設(shè)計了數(shù)據(jù)傳輸指令格式，對Linux設(shè)備驅(qū)動層次進(jìn)行了精簡，降低了協(xié)議轉(zhuǎn)換的計算開銷；批量發(fā)送請求，提高了請求提交的效率；定義了請求提交隊列和完成隊列，與調(diào)整后的請求提交過程進(jìn)行配合。實驗結(jié)果表明，新的驅(qū)動程序充分利用了Flash的并發(fā)特性和PCIe接口的高帶寬，使得存儲系統(tǒng)的性能大大提高。 2.提出了一種基于SSD內(nèi)部多通道的I/O并行調(diào)度策略。 單個的閃存顆粒讀寫帶寬一般只有幾十兆，但是現(xiàn)在主流的SSD的帶寬都有幾百兆，甚至更高，這是由于SSD可以并行執(zhí)行I/O。在SSD內(nèi)部通常有多個通道，每個通道可以獨立工作，在多通道并行的情況下，SSD的整體性能就會很高。為了充分利用SSD多通道并行性，延長SSD使用壽命，本文提出了一種SSD內(nèi)部多通道之間的I/O并行調(diào)度策略。該策略記錄每個通道的數(shù)據(jù)寫入量，每次數(shù)據(jù)刷新選擇數(shù)據(jù)寫入量最小的通道進(jìn)行寫入，以此平衡各通道寫入量。DRAM被劃分為兩部分，分別作為讀緩存和寫緩存，寫操作將數(shù)據(jù)寫入寫緩存后直接返回，寫緩存數(shù)據(jù)量達(dá)到閾值上限后觸發(fā)數(shù)據(jù)刷新操作，將部分?jǐn)?shù)據(jù)寫入SSD某個通道。與此同時，采用讀優(yōu)先策略，在讀寫請求競爭通道時讀操作優(yōu)先滿足。實驗結(jié)果表明，與傳統(tǒng)動態(tài)調(diào)度算法相比，該算法能夠更好地保證各通道數(shù)據(jù)寫入量的平衡，削弱讀寫競爭的影響，并且在一定程度上降低了系統(tǒng)的讀延遲。 3.提出一種基于磁盤和SSD的高性能混合備份存儲系統(tǒng)。 SSD性能優(yōu)越，目前已經(jīng)得到了廣泛應(yīng)用。不過，SSD寫入次數(shù)有限，可靠性不高。RAID技術(shù)被用來提高存儲系統(tǒng)的可靠性，但是在基于SSD存儲系統(tǒng)中并不適合直接采用RAID技術(shù)。本文提出了一種基于磁盤和SSD的混合備份存儲系統(tǒng)。構(gòu)建該系統(tǒng)的主要思想是：SSD對外提供服務(wù)，響應(yīng)所有I/O請求，從而使系統(tǒng)獲得比較高的性能；磁盤進(jìn)行備份，提高系統(tǒng)可靠性。為了解決磁盤寫性能較差的問題，我們設(shè)計采用了一種新的I/O重組策略，充分利用磁盤更擅長順序?qū)懙奶匦�，提高了磁盤備份SSD數(shù)據(jù)的能力。為了平抑單塊SSD上的峰值負(fù)載，我們提出了多對多協(xié)同備份策略，緩解了磁盤上的備份壓力。實驗測試結(jié)果表明，這種混合架構(gòu)具有比較高的可行性，磁盤可以提供足夠的性能滿足備份需求；相對于其他幾種類型的存儲系統(tǒng)，這種混合架構(gòu)性價比較高。
[Abstract]:The development and popularization of information technology has brought the explosive growth of data, which puts forward higher requirements on the storage system. In the past few decades, mechanical disk has become the main storage medium in the traditional storage system in terms of cost and capacity advantages. But in the data storage needs of the new situation of rapid growth under the traditional mechanical disk in the read and write delay, energy consumption and other issues have become increasingly prominent, has become the bottleneck of storage system to improve the performance. As a new type of flash storage medium, can read and write delay characteristics of low, nonvolatile, has attracted widespread attention of domestic and foreign scholars and industrial circles. The flash appears the SSD makes the bottleneck problems are solved based on the mechanical disk, with lower cost of flash, SSD is used more and more widely, much to replace the traditional mechanical hard disk trend.
This work focuses on the key technologies of PCIe SSD device driver, SSD parallel scheduling, SSD reliability storage system and other key technologies to deal with the challenging problems of SSD in terms of performance, life and reliability.
1. for the self developed PCIe solid-state memory card, the driver of the Linux operating system is designed and realized.
Most of the current mainstream SSD SATA and traditional disk the same interface, although it remains with the traditional storage system software compatibility, give full play to limit the performance of SSD. The PCIe interface SSD can make full use of high concurrency based on flash memory, a substantial increase in the SSD to read and write performance, but due to PCIe SSD the time is short, the industry has not formed a unified standard, the existing operating system storage drive are based on the traditional disk design, is not suitable for PCIe SSD. This paper designed PCIe SSD, realized the device driver under Linux. We modify the traditional Linux storage architecture is analyzed. Combined with the hardware characteristics of PCIe SSD, improved Linux storage driver model. The driver re design a data transfer instruction format, the device drivers of Linux levels were reduced, reducing the agreement The computational overhead conversion; batch sending request, to improve the efficiency of filing the request; defines the request queue and completion queue, to cooperate with the adjusted request process. The experimental results show that the new driver makes full use of the concurrency and PCIe Flash interface of high bandwidth, the system performance greatly to improve.
2. a parallel I/O scheduling strategy based on SSD internal multi-channel is proposed.
Single particle FLASH read and write only tens of megabytes of bandwidth, but now the mainstream SSD bandwidth has hundreds of megabytes, or even higher, this is because the SSD can be executed in parallel I/O. usually have multiple channels within the SSD, each channel can work independently, in a multi channel parallel situation, the overall performance will be SSD very high. In order to make full use of the SSD multi channel parallel, prolong the service life of the SSD, this paper proposes a SSD multi channel parallel I/O scheduling strategy. The strategy of writing records for each channel data, select the data written to the minimum amount of each data channel to refresh, to balance the amount of writes in.DRAM channel is divided into two parts, respectively, as read and write cache, write write data write cache directly after the return, write cache data reached the threshold limit trigger data refresh operation, will be part of the data write SSD into a channel. At the same time, using the read priority strategy, read operations read and write requests in the channel priority to meet the competition. The experimental results show that compared with the traditional dynamic scheduling algorithm, this algorithm can better ensure the balance of the amount of data written to the channel, weaken the effect of reading and writing competition, and reduced to a certain extent the system read latency.
3. a high performance hybrid backup storage system based on disk and SSD is proposed.
SSD superior performance, has been widely used. However, SSD writes a limited number, the reliability is not high.RAID technology is used to improve the reliability of the storage system, but in the SSD based storage system is not suitable for directly using RAID technology. This paper proposes a hybrid storage system and backup disk based on SSD. The main idea of the building the system is SSD to provide services in response to all I/O requests, so as to make the system get higher performance; disk backup, improve the reliability of the system. In order to solve the problem of poor performance of disk write, we design a new I/O restructuring strategy, make full use of the disk is more characteristic in order to write, improve the ability of SSD disk backup data. In order to stabilize the single peak load on SSD, we propose a more collaborative backup strategy, ease the pressure on the disk backup test. The test results show that the hybrid architecture has high feasibility. The disk can provide enough performance to meet the backup needs. Compared with other kinds of storage systems, the hybrid architecture has higher cost performance.

【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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本文編號：1613631