Solid State Drives: A Closer Look

Table of Contents

CONTENTS III

LIST OF FIGURES VI

LIST OF TABLES IX

EXECUTIVE SUMMARY 1

INTRODUCTION 3

NAND FLASH MEMORY OVERVIEW 4

• NAND Flash 4
  • Concept 4
  • Technology Evolution 6
  • NAND Flash Architecture 9
  • NAND Flash Density Trend 11
  • Page Size Trend 13
  • Block Size Trend 14
  • Read Time 14
  • Program Time 16
  • Endurance 17
  • Retention 17

SOLID STATE DRIVES 19

• What is a solid state drive? 19
• The Memory Hierarchy 19
• SSD Overview 22
• SSD Architecture 25
• Controller 27
  • Flash Translation Layer 28
  • Mapping Schemes 30
  • Bad Block Management 33
  • Wear-leveling 33
  • Garbage Collection 35
  • Error Correction 36
  • Interleaving 37
  • Power Loss Protection 37
• Techniques for Improving SSD Performance/Endurance 38
  • Caching 38
  • Flash File System Optimization 38
  • Parallelism 39
  • Flash Bus Width 40
  • Over-provisioning 40
  • Improved NAND Flash Memory 41
  • Re-mapping of Drive Block 43
• Alternative SSD Architectures 45
  • Chameleon 45
  • Hybrid SSD 46
  • HyperLink NAND 49
• SSD Reliability 52
  • Mean Time Between Failure (MTBF) 52
  • Endurance 52
  • Program Disturb 55
  • Read Disturb 55
  • Data Retention 56
  • Bit Error Rate 57
  • SMART 61

SSD VS. HDD 62

• Enterprise Applications 62
• PC Applications 66
• Low Cost Mobile PC Applications 70
• Price / GB 73

SSD LANDSCAPE 74

• Chronology 74
• Vendor Landscape 75
• Standards 76
  • IDEMA 77
  • JEDEC 77
  • Non-Volatile Memory Host Controller Interface Specification (NVMHCI) 77
  • SNIA SSD Initiative 77
  • SSD Alliance 77
  • Technical Committee T13 AT Attachment 78
• Patent Overview 79
• Seagate vs. STEC 81

COMPUTING MARKET AND APPLICATIONS 83

• Enterprise Market 83
• Transaction Processing 84
• Video Server 84
• High Performance Computing 86
• Internet/Network Server 86
• Application Workload Characteristics 86
• Server-attached vs. Storage-attached SSDs 88
• Enterprise SSD Forecast 88
• Low Cost Mobile PC Market 99
• Notebook PC Market 106
• Desktop PC Market 113
• Computing SSD Market 117
• **REFERENCES CXIX
• **ABOUT THE AUTHOR CXXI

ABOUT FORWARD INSIGHTS CXXII

• Services cxxii
• Contact cxxii

List of Figures

• Figure 1. NAND Flash Cell Programming 4
• Figure 2. Multi-level Storage in NAND Flash 4
• Figure 3. NAND Flash Cell Reading 5
• Figure 4. NAND Flash Cell Erase 5
• Figure 5. NAND Cell String 6
• Figure 6. NAND Cell String 6
• Figure 7. NAND Flash Technology Evolution 7
• Figure 8. NAND Flash Memory Gap Fill 8
• Figure 9. Electrons Stored on the Floating Gate 8
• Figure 10. Samsung 32Gb CTF Memory 9
• Figure 11. NAND Flash Memory Architecture 10
• Figure 12. 8Gb NAND Flash Memory Organization 11
• Figure 13. NAND Flash Memory Density Trend 12
• Figure 14. NAND Flash Memory Chip Size Trend 13
• Figure 15. NAND Flash Page Size Trend 13
• Figure 16. NAND Flash Block Size Trend 14
• Figure 17. NAND Flash Random Access Time 15
• Figure 18. NAND Flash Read Performance Trend 15
• Figure 19. NAND Flash Program Time 16
• Figure 20. NAND Flash Write Performance Trend 16
• Figure 21. NAND Flash Endurance Trend 17
• Figure 22. NAND Flash Endurance Trend at 70nm Technology 18
• Figure 23. NAND Flash Endurance Trend at 3xnm Technology 18
• Figure 24. Memory Hierarchy 20
• Figure 25. NAND Flash vs. DRAM Process Technology 21
• Figure 26. Major Components of SSD and HDD 22
• Figure 27. 128GB MLC SSD vs. 128GB SLC SSD Bill of Materials 23
• Figure 28. NAND Flash as a % of Bill of Material 24
• Figure 29. SSD Architecture 25
• Figure 30. Two-channel, Four-way Interleaving 26
• Figure 31. Software Architecture 26
• Figure 32. SSD Controller Functional Block Diagram 27
• Figure 33. HDD vs. SSD Address Mapping 29
• Figure 34. Flash Translation Layer 29
• Figure 35. Page Mapping 31
• Figure 36. Block Mapping 32
• Figure 37. Hybrid Mapping 33
• Figure 38. Wear-leveling 35
• Figure 39. Garbage Collection 36
• Figure 40. SSD Operating Current 39
• Figure 41. MTron PATA SSD Functional Block Diagram 40
• Figure 42. High Speed NAND 42
• Figure 43. Improving Endurance through Reduced Vt Margins 43
• Figure 44. Chameleon SSD Architecture 45
• Figure 45. Chameleon SSD Performance 45
• Figure 46. Effect of Block-level and Page-level Write Buffer 46
• Figure 47. Hybrid SSD Concept 46
• Figure 48. Data/Control Flows in Hybrid SSD 47
• Figure 49. SSD Workload Profile 48
• Figure 50. Circular Log Space in SLC NAND flash 48
• Figure 51. Hybrid SSD Endurance 49
• Figure 52. HyperLink NAND SSD vs. Conventional SSD Architecture 50
• Figure 53. Minimum SSD Capacity for 5 Year Product Life 54
• Figure 54. Program Disturb 55
• Figure 55. Read Disturb 56
• Figure 56. Flash Error Rate Surface 57
• Figure 57. SSD vs. HDD Bit Error Rates 59
• Figure 58. ECC Selection 61
• Figure 59. SSD vs. HDD Random IOPS 63
• Figure 60. SSDs vs. HDDs in the Enterprise - Performance Characteristics 65
• Figure 61. Enterprise SSD vs. HDD Average Capacity 65
• Figure 62. SSDs vs. HDDs in PCs - Performance Characteristics 67
• Figure 63. SSD Performance Trend 68
• Figure 64. Notebook PC SSD vs. HDD Average Capacity 69
• Figure 65. Desktop SSD vs. HDD Average Capacity 69
• Figure 66. SSDs vs. HDDs in Low Cost Mobile PCs - Performance Characteristics 71
• Figure 67. LC Mobile PC SSD vs. HDD Average Capacity 72
• Figure 68. SSD vs. HDD Price Curve 73
• Figure 69. HDD and SSD Landscape 76
• Figure 70. SSD Patents by Type 79
• Figure 71. SSD-related Patents by Company 80
• Figure 72. Applications Write/Read Workload 87
• Figure 73. Applications Sequential/Random Workload 87
• Figure 74. Total Enterprise SSD Units Forecast 89
• Figure 75. Total Enterprise SSD Revenue Forecast 89
• Figure 76. Enterprise Storage Drive Units Forecast 90
• Figure 77. Enterprise Storage HDD Unit Forecast 91
• Figure 78. Enterprise Storage SSD Unit Forecast 92
• Figure 79. Enterprise Storage SSD GB Forecast 92
• Figure 80. Enterprise Storage SSD GB / Unit Forecast 93
• Figure 81. Enterprise Storage SSD $ / GB Forecast 93
• Figure 82. Enterprise Storage SSD Revenue Forecast 94
• Figure 83. Enterprise Server Units Forecast 95
• Figure 84. Host Server-attached SSD Unit Forecast 96
• Figure 85. Host Server-attached SSD GB Forecast 96
• Figure 86. Host Server-attached SSD GB / Unit Forecast 97
• Figure 87. Host Server-attached SSD $ / GB Forecast 97
• Figure 88. Host Server-attached SSD Revenue Forecast 98
• Figure 89. Low Cost Mobile PC Unit Forecast 99
• Figure 90. Endurance vs. SSD Capacity 100
• Figure 91. Low Cost Mobile PC SSD Unit Forecast 101
• Figure 92. Low Cost Mobile PC SSD GB Forecast 105
• Figure 93. Low Cost Mobile PC SSD Revenue Forecast 105
• Figure 94. Notebook PC Unit Forecast 106
• Figure 95. Notebook PC SSD Unit Forecast 107
• Figure 96. Notebook PC SSD GB Forecast 112
• Figure 97. Notebook PC SSD Revenue Forecast 112
• Figure 98. Desktop PC Unit Forecast 113
• Figure 99. Desktop PC SSD Unit Forecast 114
• Figure 100. Desktop PC SSD GB Forecast 116
• Figure 101. Desktop PC SSD Revenue Forecast 116
• Figure 102. Computing SSD Unit Forecast 117
• Figure 103. Computing GB Forecast 117
• Figure 104. Computing SSD Revenue Forecast 118

List of Tables

• Table 1. SSD Bill of Materials 23
• Table 2. ECC Trend 37
• Table 3. HLNAND SSD vs. Conventional SSD 51
• Table 4. SSD Capacity as a Function of Writes / Day 54
• Table 5. Enterprise Class SSD vs. HDD 64
• Table 6. PC-Class SSD vs. HDD 66
• Table 7. Interface Transfer Speeds 68
• Table 8. Interface Transfer Speeds 68
• Table 9. Low Cost Mobile PC SSD vs. HDD 70
• Table 10. SSD Chronology 74
• Table 11. Seagate' s Patent Claims against STEC 81
• Table 12. Enterprise SSD vs. HDD Key Metrics 83
• Table 13. Video-on-Demand SSD TAM 85
• Table 14. Enterprise HDD:SSD Replacement Ratio 91
• Table 15. SSD NAND Flash Technology under Four Scenarios 100
• Table 16. LC Mobile PC SSD Capacity Unit Mix Forecast 102
• Table 17. LC Mobile PC SSD Capacity GB Mix Forecast 103
• Table 18. LC Mobile PC SLC SSD Price Forecast 103
• Table 19. LC Mobile PC MLC SSD Price Forecast 104
• Table 20. LC Mobile PC 3-bit per cell SSD Price Forecast 104
• Table 21. Notebook PC SLC SSD Capacity Unit Mix Forecast 108
• Table 22. Notebook PC SLC SSD Capacity GB Mix Forecast 109
• Table 23. PC SLC SSD Price Forecast 109
• Table 24. PC MLC SSD Price Forecast 110
• Table 25. PC SLC/3-bit per cell SSD Price Forecast 111
• Table 26. Desktop PC SSD Capacity Unit Mix Forecast 114
• Table 27. Desktop PC SSD Capacity GB Mix Forecast 115