OBJECTIVE ANALYSIS
How NAND Flash Threatens DRAM
Jim Handy
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
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
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
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
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
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?
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
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! – With awful specs!
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
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
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
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+06Price per Gigabyte
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Tape
HDD
DRAM
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L1
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Result: A Growing Gap
Cheaper & Faster
Cheaper
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
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
Ban
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)
Tape
HDD
NAND
DRAM
L3
L2
L1
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101 102 103 104 105 10610010-1
From Objective Analysis: Are Hybrid Drives Finally Coming of Age?
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
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
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
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
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
Benchmarking DRAM vs. NAND
From: How PC NAND Will Undermine DRAM
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
What If Only DRAM Mattered?
From: How PC NAND Will Undermine DRAM
1GB2GB
3GB4GB
6GB8GB
HDD
HHD
SSD0
250
500
750
1000
Scor
e
DRAM Size
750-1000500-750250-5000-250
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
What If Only Storage Mattered?
From: How PC NAND Will Undermine DRAM
1GB2GB
3GB4GB
6GB8GB
HDD
HHD
SSD100
150
200
250
300
Scor
e
DRAM Size
250-300200-250150-200100-150
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
Let’s Look At That Data Again!
From: How PC NAND Will Undermine DRAM
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
Speed/Price Advantage
60%
70%
80%
90%
100%
$60 $80 $100 $120 $140 $160 $180 $200
Price of Memory/Storage
Perf
orm
ance
Rel
ativ
e to
Bes
t Sys
tem
1GB DRAM8GB DRAM
1GB DRAM + 20GB NAND +
HDD = $80
8GB DRAM + 7GB NAND + HDD = $128
From: How PC NAND Will Undermine DRAM
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
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!”
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
Must Have: Automatic Data Placement
Source: IBM Corp. Used with Permission
0%
200%
400%
600%
800%
1,000%
All Data on HDD Table on HDD,Index on SSD
Optimalplacement
All data on SSD
Nor
mal
ized
Per
form
ance
Lev
el
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
You Can’t Do That!
• Flash is way too slow! • Flash wears out! • Flash memory is storage, not memory!
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
Is Flash Too Slow?
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2 S
hare
of A
cces
ses
Address Range
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
Which Is Better?
No SSD With SSD DRAM, Latency = 1 90% 55%
SSD, Latency = 103 0% 44%
HDD, Latency = 106 10% 1%
Ave. Latency ~105 ~104
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
What About Wear? S
hare
of W
rites
Amount of Memory
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
Flash Is Storage! What if you pretend it isn’t?
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
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
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
3D XPoint Memory
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
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
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
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
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
Cost Brought Flash Into Computing
$0
$1
$10
$100
$1,000
$10,000
Aver
age
Pric
e pe
r Gig
abyt
e
DRAM
From: Hybrid Drives: How, Why, & When?
2004: NAND Crossed DRAM
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
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
Ban
dwid
th (M
B/s
)
Price per Gigabyte
Tape
HDD
SSD
DRAM
L3
L2
L1
101
100
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3DXPoint
Source: A Close Look at the Intel/Micron 3D XPoint Memory, Objective Analysis 2015
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
How Much Does XPoint Help?
29
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
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 – It’s a new technology – that makes it harder!
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
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
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
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
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
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
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
Questions?
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
Other Information
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
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
OBJECTIVE ANALYSIS – www.OBJECTIVE-ANALYSIS.com
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 – www.OBJECTIVE-ANALYSIS.com
OBJECTIVE ANALYSIS
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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% 2015 Revenues up ~10% TBD
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