How NAND Flash Threatens DRAM - MemCon · PDF file0 SSD 250 500 750 1000 Score Size 750-1000 500-750 250-500 0-250. OBJECTIVE ANALYSIS – What If Only Storage Mattered?

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


Outline



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

•  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!


Outline



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

Ban

dwid

th (M

B/s

)

Tape

HDD

DRAM

L3

L2

L1

101

100

102

103

104

105

106

107

101 102 103 104 105 10610010-1

Result: A Growing Gap

Cheaper & Faster

Cheaper


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

dwid

th (M

B/s

)

Tape

HDD

NAND

DRAM

L3

L2

L1

101

100

102

103

104

105

106

107

101 102 103 104 105 10610010-1

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


Outline



Benchmarking DRAM vs. NAND

From: How PC NAND Will Undermine DRAM


What If Only DRAM Mattered?


1GB2GB

3GB4GB

6GB8GB

HDD

HHD

SSD0

250

500

750

1000

Scor

e

DRAM Size

750-1000500-750250-5000-250


What If Only Storage Mattered?


1GB2GB

3GB4GB

6GB8GB

HDD

HHD

SSD100

150

200

250

300

Scor

e

DRAM Size

250-300200-250150-200100-150


Let’s Look At That Data Again!



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



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!”


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


You Can’t Do That!

•  Flash is way too slow! •  Flash wears out! •  Flash memory is storage, not memory!


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


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


What About Wear? S

hare

of W

rites

Amount of Memory


Flash Is Storage! What if you pretend it isn’t?


Outline



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

$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


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

102

103

104

105

106

107

101 102 103 104 105 10610010-1

3DXPoint

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 1/5th 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!


Outline



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


Outline



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

Custom Consulting

Reports & Services


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

Documents

How NAND Flash Threatens DRAM - MemCon · PDF file0 SSD 250 500 750 1000 Score Size 750-1000 500-750 250-500 0-250. OBJECTIVE ANALYSIS – What If Only Storage Mattered?