郭大維臺灣大學：資訊工程學研究所謝仁偉Hsieh, Jen-WeiJen-WeiHsieh2007-11-262018-07-052007-11-262018-07-052006http://ntur.lib.ntu.edu.tw//handle/246246/53838快閃記憶體由於具有非揮發性、耐震及低電源消耗等特性，而被廣泛地用於行動與可攜式裝置的儲存系統中。相較靜態隨機存取記憶體而言，它具有低價格特色，與硬碟相較，它具有快速存取的優勢。在這篇論文中提出一個可靠性加強層的設計，降低誤判快閃記憶體儲存單位之儲存邏輯狀態的情況，此設計也提供廠商根據實際需要來調整系統可靠性及效能的方法。在提昇系統效能上，我們為快閃記憶體的管理提出了一個高效率的設計，可以用來有效率的辨識出熱門資料，目標是提高快閃記憶體存取的效能，並降低系統負荷及提昇垃圾收集與等量損耗的績效。論文最後藉著探索整合機械儲存媒體與快閃記憶體的輸出入裝置來研究新的電腦儲存架構，我們提出一個硬碟的快閃記憶體快取層設計，並且探討邏輯區塊位址之高效率查詢機制及垃圾收集策略。我們透過一系列的實驗來評估所提作方法的性能，並展示所提出設計的可行性。NAND flash memory is widely adopted as an alternative for storage system designs in mobile/portable devices because of its nature in non-volatility, shock-resistance, and low power consumption. It is also considered being low cost, compared to SRAM or DRAM, and having good performance, compared to disks. In this thesis, a reliability enhancement layer is designed for flash memory with single or multiple bits per cell to resolve the possibility of false identification on the logic states of flash-memory cells. It aims at providing a way to tune up the system reliability and performance, depending on the needs of different vendors. When the system performance is considered, we propose a highly efficient design for the identification of hot data for flash-memory management. It is to not only boost the system performance but also reduce the overheads and improve the efficiency in garbage collection and wear-levelling. This thesis is concluded by the exploring of device designs with mechanical and flash components. A cache layer is presented to serve as a flash-memory cache for disks. An efficient LBA lookup mechanism and a garbage collection strategy are proposed. The capability of the proposed approaches were evaluated by a series of experiments to demonstrate the effectiveness of the designs.1 Introduction ........................................... 1 1.1 Introduction ......................................... 1 1.2 System Architecture .................................. 4 1.3 Organization ......................................... 6 2 Flash-Memory Storage System with Reliability Enhancement 7 2.1 Motivation ........................................... 8 2.2 A Reliable Flash-Memory Management Framework ........ 10 2.2.1 Overview .......................................... 10 2.2.2 A Reliability Enhancement Layer ................... 12 2.2.3 A Cell-Set-Determination Algorithm ................ 16 2.3 Implementation Remarks .............................. 19 2.3.1 Reliability Analysis .............................. 19 2.3.2 Remarks: Bad Block Management ..................... 20 2.4 Summary ............................................. 22 3 Efficient Identification of Hot Data for Flash Memory Storage Systems ......................................... 24 3.1 Motivation .......................................... 25 3.2 Efficient On-Line Locality Tracking ................. 26 3.2.1 Overview .......................................... 26 3.2.2 A Multi-Dimensional Hashing Approach .............. 26 3.2.3 Implementation Strategies ......................... 31 3.3 Performance Evaluation .............................. 36 3.3.1 Experiment Setup and Performance Metrics .......... 36 3.3.2 Experimental Results .............................. 38 3.4 Summary ............................................. 42 4 Flash-Memory Cache of Hard Disks: Implementation Strategies .............................................. 43 4.1 Motivation .......................................... 43 4.2 Implementation Strategies: Flash-Memory Cache ....... 45 4.2.1 Overview .......................................... 45 4.2.2 Data Lookup and Caching ........................... 46 4.2.3 Garbage Collection and Replacement Strategies ..... 51 4.2.4 Implementation Issues ............................. 55 4.3 Performance Evaluation .............................. 58 4.3.1 Experiment Setup .................................. 58 4.3.2 Experiment Results ................................ 59 4.4 Summary ............................................. 67 5 Conclusion ............................................ 69 Bibliography ............................................ 71662789 bytesapplication/pdfen-US快閃記憶體可靠性效能flash memoryreliabilityperformancethesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/53838/1/ntu-95-D90922002-1.pdf