How NAND Flash Threatens DRAM

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BJECTIVE

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NALYSIS

How NAND Flash

Threatens DRAM

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Outline

•  Why even think about DRAM vs. NAND? •  The memory/storage hierarchy

•  What benchmarks tell us

•  What about 3D XPoint memory? •  The system of the future

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Outline

•  Why even think about DRAM vs. NAND?

•  The memory/storage hierarchy

•  What about 3D XPoint memory?

•  The system of the future

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Why Compare NAND to DRAM?

•  IT managers started telling me:

– You need less DRAM if you add an SSD

– You can sometimes even eliminate servers! •  Fewer servers means fewer software licenses

•  Why shouldn’t that would work on PCs???

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Right Way/Wrong Way

To View NAND Flash

Wrong Way •  NAND is storage •  HDD is 1/10th NAND’s cost •  NAND is expensive storage! Right Way

•  NAND is part of the memory/storage hierarchy •  NAND is 1/15th DRAM’s cost •  NAND is cheap memory!

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Outline

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The Memory/Storage Hierarchy

From Objective Analysis: Are Hybrid Drives Finally Coming of Age?

1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07

1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06

Price per Gigabyte

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NAND Fills the Gap

1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07

1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06

Price per Gigabyte

Band width (M B/ s) Tape HDD NAND DRAM L3 L2 L1 101 100 102 103 104 105 106 107 101 102 103 104 105 106 100 10-1

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Why Flash Fits

•  Speed:

– Flash is faster than HDDs – Flash is slower than DRAM

•  Price ($/GB):

– Flash is less expensive than DRAM – Flash is more expensive than HDD

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Outline

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Benchmarking DRAM vs. NAND

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What If Only DRAM Mattered?

From: How PC NAND Will Undermine DRAM

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What If Only Storage Mattered?

From: How PC NAND Will Undermine DRAM

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Let’s Look At That Data Again!

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Speed/Price Advantage

60% 70% 80% 90% 100% $60 $80 $100 $120 $140 $160 $180 $200 Price of Memory/Storage P erfo rm ance Rel ati ve to B es t S ys tem 1GB DRAM 8GB DRAM 1GB DRAM + 20GB NAND + HDD = $80 8GB DRAM + 7GB NAND + HDD = $128

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You Do Need Some DRAM!

•  There is a certain minimum DRAM

– In our benchmarks it wasn’t much: •  1GB for 8 benchmarks

•  2GB for 5 benchmarks •  3GB for 1 benchmark

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Must Have:

Automatic Data Placement

Source: IBM Corp. Used with Permission

0% 200% 400% 600% 800% 1,000%

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You Can’t Do That!

•  Flash is way too slow! •  Flash wears out!

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Is Flash Too Slow?

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What About Wear?

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Flash Is Storage!

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Outline

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Better Than NAND

NAND •  Serial read

•  Erase before write

•  Block erase/page write •  Slow write

•  Inherent bit errors •  Wear 3D XPoint •  Random read •  Overwrite •  Byte write •  Fast write

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But Cost is More Important

•  3D XPoint won’t thrive until its cost falls below DRAM

•  Technological strengths rarely offset cost •  This is a highly-competitive market

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Cost Brought Flash Into Computing

$0 $1 $10 $100 $1,000 $10,000 A ve ra g e Pr ic e p er G ig ab yte DRAM

From: Hybrid Drives: How, Why, & When?

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3D XPoint’s Role

1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07

1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06

B an d w id th (M B /s)

Price per Gigabyte Tape HDD SSD DRAM L3 L2 L1 101 100 102 103 104 105 106 107 101 ₁₀2 ₁₀3 ₁₀4 ₁₀5 ₁₀6 100 10-1 3D XPoint

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How Much Does XPoint Help?

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Getting Cheaper Than DRAM

10x as many bits in the same die area -BUT-

•  If the wafer is 2x as expensive then it is only 1/5th_{the cost}

•  Even so, yield has to be equally good

– This will take a lot of wafers

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Outline

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The System of the Future

•  Small DRAM

– HMC? HBM? – Soldered down – Not upgradeable

•  Upgradeable NVM

– The new module

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Outline

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Resources

•  A Close Look at the Intel/Micron 3D XPoint Memory Objective Analysis, September 2015

http://Objective-Analysis.com/Reports.html#XPoint

•  How PC NAND Will Undermine DRAM Objective Analysis, 2011

http://Objective-Analysis.com/Reports.html#DRAM-NAND

•  Intel/Micron 3D XPoint introduction

http://newsroom.intel.com/docs/DOC-6713

•  Intel Developer Forum (IDF) 2015 presentations

http://myeventagenda.com/sessions/0B9F4191-1C29-408A-8B61-65D7520025A8/7/5

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Minimum DRAM Sizes

1GB •  SYSmark Productivity •  SYSmark 3D •  PCMark Memory •  PCMark Productivity •  PCMark Music •  PCMark Comms •  Photoshop •  Compressing 2GB •  SYSmark E-Learning

•  SYSmark Video Creation •  PCMark TV

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Objective Analysis

Semiconductor Forecast Accuracy

Year Forecast Actual

2008 Zero growth at best. -3%

2009 Growth in the mid teens -9%

2010 Should approach 30% 32%

2011 Muted revenue growth: 5% 0%

2012 Revenues drop as much as -5% -2.7%

2013 Revenues increase nearly 10% 4.9%

2014 Revenues up 20%+ 9.9%