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Giora J. Tarnopolsky© 2003 \March ’03\1 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
Areal Density Growth:
Giora J. TarnopolskyTarnoTek - www.tarnotek.com
P.O.Box 519, Palo Alto, CA 94302-0519Phone: (650) 823-6852 Fax: (650) 322-3160
Is it the manifest destinyof the hard-disk drive?
Presented at the THIC Meeting at the Sony Auditorium,3300 Zanker Rd, San Jose CA 95134-1940
March 4-5, 2003
Giora J. Tarnopolsky© 2003 \March ’03\2 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
Single-Slide Summary
Areal Density
"HD
D P
rodu
ct D
esira
bilit
y"
There is an optimumAreal Density for whichthe HDD ProductDesirability is highest.
At the optimum AD,the capabilities of theHDD as a high-capacity,high-data-rate device thatassures data perman-ency, ruggedness, andlow manufacturing anddevelopment costs arefully manifested
Giora J. Tarnopolsky© 2003 \March ’03\3 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
Two-Slide Talk: Conclusions
Areal Density
Cap
acity
, Effi
cien
cy
EfficiencyAreal DensityProduct Capacity
As the data record-ing density increases,storage efficiency iscompromised.
ECC, servooverhead, mechanism
The users’ capacitywill not grow with the“native” areal density of1/(bit dimensions)
Diminishingperformance returns
Giora J. Tarnopolsky© 2003 \March ’03\4 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
Outline
Introduction - at a brisk paceEvolution of useful productsTradeoff: feasibility vs. desirability
Developments 1990 - 20021 Terabit/in2 proposalsCapacity scalingThe value add of A.D.
Giora J. Tarnopolsky© 2003 \March ’03\5 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
IntroductionAreal density has grown from 1 Gb/in2 in 1990to ~150 Gb/in2 by November 2002Feasibility assessments of 1 Tb/in2 have beenpublished, stated INSIC Goal10, 50 Tb/in2 have been suggested for HAMR
HDD future predicated oncontinuing growth of the
areal density
Giora J. Tarnopolsky© 2003 \March ’03\6 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
IssuesData storage at 1 Tb/in2 is possibleMaterials and systems research for 1 Tb/in2 isscientifically sound
These are not in question!Is it desirable to accomplish
≥ 1 Tb/in2 products?What constraints on user features
does 1 Tb/in2 impose?What is the return on investment?
Giora J. Tarnopolsky© 2003 \March ’03\7 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
265 Tb/in2 virtually demonstrated
S. Heinze, M. Bode, A. Kubetzka, O. Pietzsch, X. Nie, S. Blügel,R. Wiesendanger, Science 288 (2000) 1805-1808: Real-Space Imaging
of Two-Dimensional Anti-ferromagnetism on the Atomic Scale
R. Wiesendanger & M. Bode, Solid State Communications119(2001) 341-355: Nano- and atomic-scale magnetism studied byspin-polarized scanning tunneling microscopy and spectroscopy
Single atomic layer of Mn onW(110) forms a two-dimensionalantiferromagnet.
These are magnetic monolayers ofchemically equivalent atoms, whereadjacent atoms at nearest-neighbor siteshave opposite magnetic moments.
The single-atom spin has beenresolved by Spin-Polarized Scan-ning Tunneling Spectroscopy
AD ≥ 265 Tb/in2 for a 12-atom bit
non-magneticW tip
magneticFe tip
Full imagesize is2.7 x 2.2 nm2
4.5 ± 0.1 Å
… and
Giora J. Tarnopolsky© 2003 \March ’03\8 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
… the drive is … “just engineering”
Ready for Fry’s?
Giora J. Tarnopolsky© 2003 \March ’03\9 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
Nearly Perfect Inventions
Some inventions are born perfectThis assures their permanency …… and defines the domain of development
Examples of perfect inventions are the bicycle,the umbrella, the book, and the disk drive
Giora J. Tarnopolsky© 2003 \March ’03\10 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
Gyroscopic effect assures stability of the riderUnder torque T, the bike turns but does not fall
Low ratio of vehicle mass to rider mass~ 15 % (as compared to ~2,200% for car)
EfficientRuggedMass-producedAffordable
Nearly Perfect Inventions: Bicycle
Lr
dtLdr
Tr
Giora J. Tarnopolsky© 2003 \March ’03\11 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
2-D travel with only one linear motionHigh volumetric densityRandom accessMass-producedNon-volatileAffordableRugged
Disk Drives - Nearly Perfect Invention
Few-hundred $/boxNo vibration isolation, no T stabilization
These properties define drives
Giora J. Tarnopolsky© 2003 \March ’03\12 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
Areal Density and Storage CostsAreal Density BenefitsFewer components
HeadsDisksSpindles
Volumetric density
No AD BenefitData storagemanagement (s/w & h/w)
Data permanencyRuggednessElectronicsInterfacesCapital & Test Equip.
Giora J. Tarnopolsky© 2003 \March ’03\13 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
0
100
200
300
400
500
0 80 160 240Capacity (GB)
Reta
il Pr
ice
($)
HITACHIIBMMAXTORSEAGATEWESTERN DIGITAL
Source CDW, 2/2003
Cost vs. Capacity, 7200 rpmChart shows current retailunit prices (not best price)Thus, a 1 Tbyte driveshould cost about $2,000.Right?Not quite!No. 1: The “box” wouldnot sell above
Price =$ (n × 100),where n < 5
No. 2: For larger capacities, the cost ofmanaging the data exceeds the H/W cost
“The price the customer is willing to pay determines allowable costs.” P. Drucker
Giora J. Tarnopolsky© 2003 \March ’03\14 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
1 Tbyte Storage Example - early 2003Fantom Drive 960 GB G-Force RAID LX
8 x 120 GB EIDE drives, 7200 rpmHost: Any SCSI host computer, 160 MB/sSpecial vibration or temperature handling: NoneHot-swappable everything (RAID 1,3,5)MTBF: 500,000 hs
Retail on 2/24/03: $7,609.44EIDE drives’ @ Fry’s: $960.00
Non-AD cost: 87%O/S independent, data management, redundancy, profit ...
960GB, 8-drive, 8-bay,Ultra3 SCSI (Ultra160/m),
EIDE backplane,rackmount RAID
(RAID levels 0,1,0+1,3 and 5) hot swappable drives
Giora J. Tarnopolsky© 2003 \March ’03\15 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
From 1 to 150 Gb/in2: 1990 - 2002Extraordinary
achievementLog- log plot of track
density and linear densityThe hyperbolae are lines
of constant areal densityThe rays from the origin
are lines of constant bitaspect ratio
Low AD demos hadbetter BER than recentdemos
From about 1 Gb/in2, theBAR has changed from~ 25 to ~ 3 to 4Linear Density (kbpi)
Trac
k D
ensi
ty (k
tpi)
Hitachi PMRFujitsuIBMSEGReadRiteHitachi Long.
© G Tarnopolsky 2002
20
BAR
1
2
4
812
16
250
100
200
806050
30
20
10
20
10
30
4050
75
100
200
Gb/in2
200 1000800600100 400300
P
PP
PP
/ Perp
5
25
15
Giora J. Tarnopolsky© 2003 \March ’03\16 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
Linear Density (kbpi)
Trac
k D
ensi
ty (k
tpi)
Hitachi PMRFujitsuIBMSEGReadRiteHitachi Long.WoodMallaryGao & BertramVictora
© G Tarnopolsky 11/2002
20
BAR1
24
8
12 16
600
300500
200
100
50
3020
10
2010
30405075
100
200
Gb/in2
P P
P
/ Perp
5
25
200 1000700100 500300 2000 3000
1k
500
P
P
From 0.1 to 1.0 Tb/in2
At the 2000 MMMConference, PMR resultsbetween 100 to 145Gb/in2, and longitudinalresults at ~ 150 Gb/in2
were shownFour 1 Tb/in2 studiesR. Wood et al., IBMM. Mallary et al., MaxtorGao & Bertram, UCSD-
CMRRR. R. VictoraVictora, UM - MINT, UM - MINTThese studies explore
the regime of ~ 2 Mbpi &~ 500 ktpi
Giora J. Tarnopolsky© 2003 \March ’03\17 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
Early Demos, 1 Tb/in2 StudiesC. Tsang et al., IEEE Trans. Mag., vol. 26, p. 1689, Sept. 1990. T. D. Howell et al., ibid., p. 2298.
J. Hong et al., IEEE Trans. Mag., vol. 38, p. 15, 2002. (Fujitsu demo)
Z. Zhang et al., IEEE Trans. Mag. vol. 38, p. 1861, Sept. 2002. (Seagate demo)
F. Liu et at, presented at InterMag 2002, Amsterdam, The Netherlands, April 2002 (ReadRite-MMC demo.)
IBM Travelstar 80GN, Model No. IC25N080ATMR04, Nov. 2002.
47th MMM Conference 2002, announcements by Seagate & ReadRite.
R. Wood et al., IEEE Trans. Mag., vol. 38, p. 1711, 2002.
M. Mallary et al, IEEE Trans. Mag., vol. 38, p. 1719, 2002.
K. Gao and N. Bertram, to be published IEEE Trans. Mag., TMRC 2002, Santa Clara, CA, USA,August 2002.
R. Victora et al., IEEE Trans. Mag., vol.38, p. 1886, Sept. 2002.
M. Kryder et al., presented at TMRC 2002, Santa Clara, CA, USA, August 2002.
Giora J. Tarnopolsky© 2003 \March ’03\18 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
0
100
200
300
400
500
600
700
800
900
1000
0 20 40 60 80 100 120 140 160Areal Density (Gb/in2)
Line
ar D
ensi
ty (k
bpi)
0
50
100
150
200
250
300
350
400
450
500
Trac
k D
ensi
ty (k
tpi)
HitachiFujitsuIBMReadRiteSEGSEG PerpRR Perp
P
PP P
PP
P
P
P
© G Tarnopolsky 11/2002
P
How the Areal Density Was WonLinear and track
density vs. arealdensity
Track densityincreased by ~ 35,caused most ofthe areal densitygain.
Enabled by theadvent of spinvalve and GMRheads, advancesin head fabric-ation techniques,media SNR
The inflection point inThe inflection point inthe linear density curvethe linear density curvereflects media SNRreflects media SNRbarriers, the onset ofbarriers, the onset ofthermal decay, andthermal decay, andmagnetic spacingmagnetic spacing
Giora J. Tarnopolsky© 2003 \March ’03\19 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
Areal densitydemonstrationsare rigorous,comprehensiveassessments ofthe technology
The BER hasworsened withincreasing arealdensity ofdemos
The 100 ~ 200Gb/in2 regime isan importantresearch field
A Moving BER Target
-11
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
0 20 40 60 80 100 120 140 160Areal Density (Gb/in2)
Log(
On-
trac
k B
it Er
ror R
ate)
IBMFujitsuHitachiReadRiteSeagateSeagate PerpRR Perp
© G Tarnopolsky 11/2002
Giora J. Tarnopolsky© 2003 \March ’03\20 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
0
100
200
300
400
500
600
700
800
900
0 20 40 60 80 100 120 140
Areal Density (Gb/in2)
Line
ar D
ensi
ty (k
bpi)
0
10
20
30
40
50
60
70
80
90
Hea
d-M
edia
Sep
arat
ion
(nm
)
HitachiFujitsuIBMReadRiteSEGSEG Perp
P
P
PP
PP
Head-Media Separation: Downtrack Story
As therecordingwavelengthdecreased, theHMS shrunkfrom ~ 80 nm to~ 10 nm
Extraordinaryefforts put inreduction ofpole-tiprecession,carbon overcoatthickness, flyingheight and lube
Giora J. Tarnopolsky© 2003 \March ’03\21 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
0
20
40
60
80
100
120
140
160
180
200
0 20 40 60 80 100 120 140 160 180 200Inverse Flying Heigth (µm-1)
Are
al D
ensi
ty (G
b/in
2 )
0.0
0.3
0.6
0.9
1.2
1.5
1.8
2.1
2.4
2.7
3.0
Loss
Fac
tor 2
π d
/ λ
Areal Density 1990 - 2002Spacing Loss Factor k*d1 Tbit k*d valuesPoly. (Areal Density 1990 - 2002)
1 Tb/in2 k*d arrowsGao & BertramMallary et al.Wood et al
Flying Height et al.: Finite ResourcesAbscissae are
inverse flyingheight, an open-ended scale
100 Gb/in2
demo’s FH = 60 ÅFlying height is
but one componentof the head-mediaseparation
e-(2π•HMS/λ) spacingloss factor. kdplotted
50 nm or ~100 atomic
layers5 nm or
~ 10atomiclayers
0
5
10
15
0 250 500 750 10001/FH (µm-1)
HM
S (n
m)
Head-MediaSeparation
10 Å20 Å
Giora J. Tarnopolsky© 2003 \March ’03\22 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
1 Tb/in2 TMR: A Different Future
Distribution of Lattice Constants
0
5
10
15
0 0.5 1 1.5 2Lattice Constants (nm)
Freq
uenc
y
Elements Ferrites Garnets 1-σ TMR
In the 1 Tb/in2
regime, 500 ktpi, the1σ TMR (trackmisregistration) isabout 1.5 nm
The permissible TMRis of the order ofmagnitude of latticeconstants
This is not the caseat 1, 10, or 100 Gb/in2
Giora J. Tarnopolsky© 2003 \March ’03\23 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
Capacity will not grow linearly with ADThe capacity of a product will not grow linearlywith areal density
The limited SNR of high AD demands higher ECCoverheadThe limited PES (position error signal) SNR requireshigher servo overheadTMR of O(nanometer) requires smaller arm lengthsand platter diameters
The effective user areal density becomes muchlower that that given by the bits’ dimensions
Giora J. Tarnopolsky© 2003 \March ’03\24 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
ScalingCapacity = areal density x area x ECC efficiencyx servo efficiency and also mechanical limits
Capacity is a parametric function of themechanism.
( ));,,(
)1()1(2 22
mechanismRTDLDfCrRTDLDC servoECC
=−×−×−×××= ψψπ
Giora J. Tarnopolsky© 2003 \March ’03\25 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
Parametric dependencies: MechanismConstraints: immunity fromexcessive vibration that causesTMR, and access timeNumber of requests N per unit timefrom the host to the drive
Data throughput leads to accesstimes inversely related to the drivecapacity
τ11~~ =
>< timeaccessfiledatausercapacityN
Otherwise, capacitywasted
Mom was right.Mom was right.30,000 rpm30,000 rpm
isn’t fastisn’t fastenough ...enough ...
Giora J. Tarnopolsky© 2003 \March ’03\26 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
Parametric dependencies: MechanismAccess time is a function of the applied torqueto the actuator arm. Large torque produceslarge bending moment in the arm and excitesdeflections from nominal positionImpose a desirable access time, determine thenecessary torque, estimate the magnitude of theamplitude of residual vibration after actuationAmplitude of vibration is measured against trackpitch
Giora J. Tarnopolsky© 2003 \March ’03\27 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
Actuator arm mechanismis analogous to
helicopter’s blade
Dover Publishers 1994Princeton Univ. Press 1980
Deflection of flexureacceleration
acce
lera
tion
velocity
velo
city
space
time
arc
leng
th
α
l
R
h
R: disk radiusl: arm lengthh: width at pivota: acceleration at headω: angular velocityα: angles: = lα = arc lengthm massIm: moment of inertia w.r.t.
pivot
Torque for actuator sweep of arc lα cm in τ seconds
Giora J. Tarnopolsky© 2003 \March ’03\28 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
Torque;
dtdI
dtdLT mact
ω==
;646
222 mlhlmIm ≈
+=
α
l
R
h
.42τ
αω==
la
dtd
2
3
2
2
332
ταρ
τα AlmlTact ==
Giora J. Tarnopolsky© 2003 \March ’03\29 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
Deflection at the head position
TPnEIlA
EIlTs
oo
actact ×===∆ 2
52
61
21
ταρ
The flexure deflection by the bending momentof actuation should be compared against thetrack pitch.
E: Young’s modulusIo: moment of inertia
(cross- section)Α: cross section areaρ: density
α
l
R
h
Giora J. Tarnopolsky© 2003 \March ’03\30 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
Capacity vs. Areal Density (I)
Disk radius R ~ arm lengthWith a constraint on the amplitudeof vibration of the arm, the capacitygrows slower than linearly with TD:
52
52
22 16
⋅
=
TDAEInl o
αρτ
535
2262 TDLDA
EInC oact ⋅⋅
=
αρτπ
track density (ktpi)
arm
leng
th (c
m) 10 ms
5 ms
10 30 50 100 300 500
6
5
4
3
2
7
per platter
Giora J. Tarnopolsky© 2003 \March ’03\31 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
Non-repeatable PerturbationsA different scaling attains if the drive’senvironment creates a random, non-repeatabletorque of rms value Ťnr
. For instance, in a RAIDTnr has a probability distribution, and a 3-σ TMRevent would happen for a 3-σ Tnr occurrenceThe rms arm deflection is
o
nrnr EI
lTs2
21(
=∆
Giora J. Tarnopolsky© 2003 \March ’03\32 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
Non-repeatable Arm DeflectionThe non-repeatable arm deflection is equated to the 1-σ TMR,
The arm length is:
For a constant disk radius, the ambient perturbations mustdecrease linearly with track density. If Ťnr does not decrease,then the disk must become smaller.
TDTMRO
EIlTso
nrnr 30
1)1(21 2
=≈=∆ σ(
nr
o
TTDIEl (⋅⋅
⋅=
3022
∆snr
Giora J. Tarnopolsky© 2003 \March ’03\33 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
Capacity vs. Areal Density (II)
Disk radius R ~ arm lengthWith a constraint from irreducibleŤnr , the capacity is:
LDTIETDLD
TTDIEC
nr
o
nr
onr ⋅
⋅⋅
=⋅⋅
⋅⋅
⋅= ((
3022
3022 ππ
nr
o
TTDIEl (⋅⋅
⋅=
3022
10 30 50 100 300 500track density (ktpi)
6
5
4
3
2
arm
leng
th (c
m)
1-σ T nr at 100 ktpi
Giora J. Tarnopolsky© 2003 \March ’03\34 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
Capacity vs. Areal Density (III)BAR: 7.2 4τ : 10 5 ms1 Tb/in2 may
not be cost-effective forproducing ahigher capacitydrive withtoday’s low priceand ruggedness0
200
400
600
800
1000
1200
1400
0 200 400 600 800 1000
Areal Density (Gb/in2)
Capa
city
(GB/
plat
ter)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Dia
met
er (i
nch)
UnrestrictedActuation, 10 tracksAct, 10 tracks,150 GbNon-repeatable torque, 1-sNon-rep, 1-s, 150 GbDiameter (act)
Giora J. Tarnopolsky© 2003 \March ’03\35 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
Capacity ~ (Areal Density)α, 0< α<<1The requirement of a rugged, inexpensivedevice leads to a capacity growth significantlyslower than the areal density growthThe limited SNR expected at ~ 2 Mbpi likewiselimits the capacity growth due to an increasingECC overhead, e.g., 35% at 9.5 dB (rms/rms) inWood et al. analysisThere is a technological and economicaloptimum areal density that would enablepowerful, useful products below 1 Tb/in2
Giora J. Tarnopolsky© 2003 \March ’03\36 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
The 20 dB, 200 Gb/in2, $200 Challenge
0.5 Terabyte in mobile format, high rpm & data rateDesirable, rugged, affordable, universally used. Raid 5.
ParametersAD 200 Gb/in2
LD 1000 kbpiTD 200 ktpiSNRsys ≥ 20 dBThermal decay < 0.5 %/decadeRotation ≥ 7200 rpmDisk 65 mmCapacity 120 GB/platterTransfer rate ≥ 250 Mbyte/sOperating T 5 - 55 ° COperating shock 200 GNo slider-level microactuator
DriveCapacity 480 GBPlatters 4Heads 8Weight 155 gRetail price <<200 $
SystemCapacity 3.84 TBDrives 8Physical size
Width 9 inHeight 4.25 inDepth 6 in
Price <2,400 $
Giora J. Tarnopolsky© 2003 \March ’03\37 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
The disk “tape” challengePsychological adherence to tapeA disk “tape” cartridge is possible and useful200 GB in LTO/DLT cartridge formatNon-op shock: 10-ft drop, any and all axesHot-swappablePrice = Tape cartridge/2Bandwith = 2 x BW(tape)Shelf-life: indefinite
TAPETAPETAPETAPETAPE
DISKDISKDISKDISKDISK
Giora J. Tarnopolsky© 2003 \March ’03\38 Areal Density Growth TARNOTEK
THIC - The Premier Advanced Recording Technology Forum
The value ADD of AD GrowthOptimum areal density is that which delivers:
Data PermanencyAbsolute non-volatility // Fixed content // Regulatory compliance
ReliabilityRuggednessSNRsys
Bandwidth and IOPSProduct Longevity
Areal Density Plateau: Extended product cycles