hybrid solid state drives for · muthukumar murugan et al. [mascots’12]! • data distribution as...
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![Page 1: Hybrid Solid State Drives for · Muthukumar Murugan et al. [MASCOTS’12]! • Data distribution as a typical approach!! Impact on performance and lifetime! 3 Hybrid SSD Architectures](https://reader034.vdocument.in/reader034/viewer/2022050405/5f821da3980fda45a64e8775/html5/thumbnails/1.jpg)
Hybrid Solid State Drives for Improved Performance and Enhanced Lifetime"
Yongseok Oh" Jongmoo Choi!
Donghee Lee! Sam H. Noh!
Hongik [email protected]
University of Seoul!{ysoh, kckjn97, dhl_express}
@uos.ac.kr
Dankook [email protected]
Eunjae Lee!
![Page 2: Hybrid Solid State Drives for · Muthukumar Murugan et al. [MASCOTS’12]! • Data distribution as a typical approach!! Impact on performance and lifetime! 3 Hybrid SSD Architectures](https://reader034.vdocument.in/reader034/viewer/2022050405/5f821da3980fda45a64e8775/html5/thumbnails/2.jpg)
29th IEEE Conference on Mass Storage Systems and Technologies (MSST’13) !
• SSDs are being increasingly deployed!• MLC(2bits) and TLC(3bits) flash chips are considered!
§ Pros: cost effectiveness !§ Cons: high write latency, low endurance !
• Hybrid Approach is needed (e.g., SLC+MLC SSDs, SLC+TLC SSDs,)!
2
Introduction
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SLC MLC TLC
$/GB
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40,000
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SLC MLC TLC Write Latency (us)
P/E Cycles
P/E Cycles Write Time (us)
Source: www.DRAMeXchange.com! Source: www.micron.com!
High Latency
Low Endurance
Cost effective!
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29th IEEE Conference on Mass Storage Systems and Technologies (MSST’13) !
• Existing works!§ Li-Pin Chang [ASPDAC’08]!§ Sungjin Lee et al. [ATC’09]!§ Soojun Im et al. [SAC’09]!§ Muthukumar Murugan et al. [MASCOTS’12]!
• Data distribution as a typical approach!§ Impact on performance and lifetime!
3
Hybrid SSD Architectures
Data Distributor"
Write Request (Data)!
Hybrid Solid State Drive!
Hot Data" Cold Data"
SLC! TLC!High performance!High endurance!
Large capacityCost efficiency!
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29th IEEE Conference on Mass Storage Systems and Technologies (MSST’13) !
Static Data Distribution"• Distributed based on amount of data!• How to determine optimal amount of hot data? !
§ More hot data or less hot data to SLC SSD?!
4
Problem and Motivation
Hot Data! Cold Data!
Static"SLC SSD! TLC SSD!
More hot data stored in SLC SSD!!
Increased GC cost, !Shortened Lifetime!of SLC SSD!
Hot Data! Cold Data!
Static"SLC SSD! TLC SSD!
Less hot data stored in SLC SSD!
Increased GC cost, !Shortened Lifetime!of TLC SSD!
![Page 5: Hybrid Solid State Drives for · Muthukumar Murugan et al. [MASCOTS’12]! • Data distribution as a typical approach!! Impact on performance and lifetime! 3 Hybrid SSD Architectures](https://reader034.vdocument.in/reader034/viewer/2022050405/5f821da3980fda45a64e8775/html5/thumbnails/5.jpg)
29th IEEE Conference on Mass Storage Systems and Technologies (MSST’13) !
Static Data Distribution"• Distributed based on amount of data!• How to determine optimal amount of hot data? !
§ More hot data or less hot data to SLC SSD?!
5
Problem and Motivation
Q: How do we adjust the distribution?!A: Analytic Model based Dynamic Approach!
Hot Data! Cold Data!
Static"SLC SSD! TLC SSD!
More hot data stored in SLC SSD!!
Increased GC cost, !Shortened Lifetime!of SLC SSD!
Hot Data! Cold Data!
Static"SLC SSD! TLC SSD!
Less hot data stored in SLC SSD!
Increased GC cost, !Shortened Lifetime!of TLC SSD!
![Page 6: Hybrid Solid State Drives for · Muthukumar Murugan et al. [MASCOTS’12]! • Data distribution as a typical approach!! Impact on performance and lifetime! 3 Hybrid SSD Architectures](https://reader034.vdocument.in/reader034/viewer/2022050405/5f821da3980fda45a64e8775/html5/thumbnails/6.jpg)
29th IEEE Conference on Mass Storage Systems and Technologies (MSST’13) !
• Perf scheme!§ Re-distributes hot and cold data for the performance!§ Employs analytic model to find the hot and cold data distribution!
u Determines optimal sizes of hot and cold data!§ Considers GC cost and workload pattern!
• Life scheme!§ Calibrates performance optimized distribution of Perf scheme!§ Uses relative remaining lifetime metric!
u ELEFTSLC, TLC: the remaining erase cycles!
u EUSEDSLC, TLC: the used erase cycles!
6
Analytic Model Based Dynamic Approach
LSLC =ESLC
LEFT
ESLCUSED
LTLC =ETLC
LEFT
ETLCUSED(SLC Lifetime)! (TLC Lifetime)!
AnalyGcal Model: CHYSSD Read the paper for detailed derivations!
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29th IEEE Conference on Mass Storage Systems and Technologies (MSST’13) ! 7
Performance Optimization
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Res
pons
e Ti
me(
ms)
Logical Time
StaticPerf
Performance improves!
0.5 0.6 0.7 0.8 0.9
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SLC
Util
izat
ion
Logical Time
StaticPerf 0.7
0.75
0.8
0.85
0.9
TLC
Util
izat
ion
Logical Time
StaticPerf
!!!
Cold!Data !Size!
!
!!!
Hot !Data!Size!
!!
Res
pons
e Ti
me
!
Static Scheme"
Fixed data distribution!
Perf Scheme (Dynamic)"
GC cost model! Workload pattern!
Analytic Model (CHYSSD)!
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29th IEEE Conference on Mass Storage Systems and Technologies (MSST’13) !
• Maximizing the lifetime of the hybrid SSD !§ Evenly utilize the lifetime of SSDs!
8
Lifetime Optimization
Time!
Hot Data!
100%"
SLC!
100%"
TLC!=!
Initial!Relative
Remaining Lifetime!
"""
""""
Due to similar lifetime"
Time!
Cold Data!
"""
""""
95%"
SLC! >! TLC!70%"
TLC!
Younger!
Older!
"""
""""
"
<!TLC!40%"
SLC!25%"
SLC!
Younger!
Older!
Perf!Life!
Increase hot data"Due to younger SLC"
Decrease cold data"Due to older TLC"
Decrease hot data"Due to older SLC"
Increase cold data"Due to younger TLC"
Lifetime improve "Performance degrades"
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29th IEEE Conference on Mass Storage Systems and Technologies (MSST’13) !
• Hybrid SSD Simulator: DiskSim + SSD Extension!
• Various schemes!§ Static: fixed size of hot and cold data!§ Dynamic: Perf, Life "
• Configurations !§ ST-SSD: 2GB SLC + 16GB TLC SSDs!§ MT-SSD: 2GB MLC + 16GB TLC SSDs (in the paper)!
• Usable address space: 16GB!§ Hot data size cannot be larger than capacity of SLC SSD!
• Realistic workload traces: Exchange and Financial (in the paper)!
9
Experimental Setup
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29th IEEE Conference on Mass Storage Systems and Technologies (MSST’13) !
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Life=m
e
Hot Data Size (GB)
Hybrid SSD Life=me
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0.1 0.4 0.8 1.2 1.6 1.9
Respon
se Tim
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s)
Hot Data Size (GB)
Hybrid SSD Performance
StaGc Perf Life
• Static scheme!§ Response times are varied according to hot data size!
• Perf scheme achieves the improved performance!
• Life scheme enhances the lifetime of a hybrid SSD!§ Lifetime metric: min(LSLC, LTLC)!§ Hybrid SSD is alive when two SSDs are working!
! 10
Evaluation Results
Maximum of SLC Capacity (2GB)!
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29th IEEE Conference on Mass Storage Systems and Technologies (MSST’13) !
0
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0.1 0.4 0.8 1.2 1.6 1.9
Nor
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lized
GC
Tim
e
Hot Data Size (GB)
GC Time
• Static scheme shows varied GC times along with hot data size!• Perf scheme presents reduced GC time !
§ GC cost is considered!§ (Life scheme is omitted due to similar trend)!
11
Analysis of Result
Static TLC! Static SLC!
Perf SLC (Dynamic)"
Perf TLC (Dynamic)"
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29th IEEE Conference on Mass Storage Systems and Technologies (MSST’13) !
• Dynamic data distribution schemes!§ Analytical model approach!§ Perf scheme optimizes performance!§ Life scheme enhances lifetime!
• Future direction!§ Memory efficient hot-cold data classifier!§ Emerging write amplification models!
12
Concluding Remarks
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29th IEEE Conference on Mass Storage Systems and Technologies (MSST’13) ! 13
Yongseok Oh! Jongmoo Choi! Donghee Lee!Sam H. Noh!
Hongik [email protected]
University of Seoul!{ysoh, kckjn97, dhl_express}
@uos.ac.kr
Dankook [email protected]
Hybrid Solid State Drives for Improved Performance and Enhanced Lifetime
Eunjae Lee!