How NAND Flash Threatens DRAM

How NAND Flash Threatens DRAM Jim Handy OBJECTIVE ANALYSIS

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 Questions

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??? Why not on all computer types?

Right Way/Wrong Way To View NAND Flash Wrong Way NAND is storage Right Way NAND is part of the memory/storage hierarchy HDD is 1/10 th NAND s cost NAND is expensive storage! NAND is 1/15 th DRAM s cost NAND is cheap memory! With awful specs!

The Memory/Storage Hierarchy 1.E+07 10 7 1.E+06 10 6 1.E+05 10 5 Cheaper & Faster L2 L1 Bandwidth (MB/s) 1.E+04 10 4 1.E+03 10 3 Cheaper DRAM L3 1.E+02 10 2 HDD 1.E+01 10 1 Tape Result: A Growing Gap 1.E+00 10 0 1.E-01 10-1 1.E+00 10 0 1.E+01 10 1 1.E+02 10 2 1.E+03 10 3 1.E+04 10 4 1.E+05 10 5 1.E+06 10 6 Price per Gigabyte From Objective Analysis: Are Hybrid Drives Finally Coming of Age?

NAND Fills the Gap 10 7 1.E+07 10 6 1.E+06 L1 10 5 1.E+05 L2 Bandwidth (MB/s) 10 4 1.E+04 10 3 1.E+03 NAND DRAM L3 10 2 1.E+02 HDD 10 1 1.E+01 Tape 1.E+00 1.E-01 10-1 1.E+00 10 0 1.E+01 10 1 1.E+02 10 2 10 1.E+03 10 1.E+04 1.E+05 10 5 1.E+06 10 6 10 0 Price per Gigabyte From Objective Analysis: Are Hybrid Drives Finally Coming of Age?

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 Bonus: It s nonvolatile

Benchmarking DRAM vs. NAND From: How PC NAND Will Undermine DRAM

What If Only DRAM Mattered? 1000 750 Score 500 250 750-1000 500-750 250-500 0-250 0 1GB 2GB 3GB DRAM Size 4GB SSD HHD 6GB HDD 8GB From: How PC NAND Will Undermine DRAM

What If Only Storage Mattered? 300 250 Score 200 150 250-300 200-250 150-200 100-150 100 1GB 2GB 3GB DRAM Size 4GB SSD HHD 6GB HDD 8GB From: How PC NAND Will Undermine DRAM

Let s Look At That Data Again! From: How PC NAND Will Undermine DRAM

Speed/Price Advantage 100% 1GB DRAM 8GB DRAM Performance Relative to Best System 90% 80% 70% 1GB DRAM + 20GB NAND + HDD = $80 8GB DRAM + 7GB NAND + HDD = $128 From: How PC NAND Will Undermine DRAM 60% $60 $80 $100 $120 $140 $160 $180 $200 Price of Memory/Storage

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 After that, NAND was cheaper More Boost for the Buck!

1,000% Must Have: Automatic Data Placement Normalized Performance Level 800% 600% 400% 200% 0% All Data on HDD Table on HDD, Index on SSD Optimal placement All data on SSD Source: IBM Corp. Used with Permission

You Can t Do That! Flash is way too slow! Flash wears out! Flash memory is storage, not memory!

2Share of Accesses Is Flash Too Slow? 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 Address Range

Which Is Better? No SSD With SSD DRAM, Latency = 1 90% 55% SSD, Latency = 10 3 0% 44% HDD, Latency = 10 6 10% 1% Ave. Latency ~10 5 ~10 4

What About Wear? Share of Writes Amount of Memory

Flash Is Storage! What if you pretend it isn t?

3D XPoint Memory

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 Lower error rates Low wear

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 Memories are a commodity

Cost Brought Flash Into Computing Average Price per Gigabyte $10,000 $1,000 $100 $10 $1 2004: NAND Crossed DRAM DRAM $0 From: Hybrid Drives: How, Why, & When?

3D XPoint s Role 10 7 1.E+07 10 6 1.E+06 L1 10 5 1.E+05 L2 Bandwidth (MB/s) 10 4 1.E+04 10 3 1.E+03 10 2 1.E+02 SSD 3D XPoint DRAM L3 HDD 10 1 1.E+01 Tape 10 0 1.E+00 1.E-01 10-1 1.E+00 10 0 1.E+01 10 1 1.E+02 10 2 10 1.E+03 10 1.E+04 10 1.E+05 10 1.E+06 Price per Gigabyte Source: A Close Look at the Intel/Micron 3D XPoint Memory, Objective Analysis 2015

How Much Does XPoint Help? 29

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 1/5 th the cost Even so, yield has to be equally good This will take a lot of wafers It s a new technology that makes it harder!

The System of the Future Small DRAM HMC? HBM? Soldered down Not upgradeable Upgradeable NVM The new module Could be either NAND or 3D XPoint

Questions?

Other Information

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 36

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 PCMark Game Decompressing

OBJECTIVE ANALYSIS Profound Analysts Reports & Services Custom Consulting

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% 2015 Revenues up ~10% TBD