CAVE : Channel-Aware Buffer Man-agement Scheme for Solid State

DiskSAC '11

Sungkyu Park, Youngwoo Park, Gyudong Shim and KyuHo Park From KAIST

2011. 06. 02 (Thu)Kwangwoon univ. SystemSoftware Lab.

HoSeok Seo1

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Introduction The General Architecture of SSD

Maximize the performance with the parallelism utilizing 4 channels and 2 Ways

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Introduction Multi-channel FTL Scheme

To Achieve the maximum of parallelism- I/O operations are performed in a clustered page unit- Erase operations are performed in a clustered block unit

Related FTL schemes- MCsplit Scheme, the SubGroup Scheme, etc…

1-channel FTL Scheme Low garbage collection overhead instead of a multi-

channel FTL

Related FTL Schemes- BAST, FAST, LAST, etc…

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Introduction 1-channel FTL Scheme vs Multi-channel FTL

Scheme

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What is CAVE? CAVE (Channel-aware victim eviction) is

Buffer Management Scheme proposed to achieve good write performance in 1-ch FTL like multi-ch

FTL Scheme used with 1-channel FTL and other buffer Management Scheme

What is Different between CAVE and other buffer man-agement?

Other buffer management - Focus on which data have to are evicted ( = eviction order )- Related buffer scheme : CFLRU, BPLRU, FAB, REF, CLC

CAVE- Focus on How many victims have to are evicted ( = eviction rate )

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CAVE Algorithm

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Experimental Setup Used scheme list for experiment

FTL- 1-Channel FTL Scheme : BAST- Multi-Channel FTL Scheme : MCsplit

Buffer Management Scheme- Page-level LRU : CFLRU- Block-level LRU : BPLRU

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Experimental Setup

- Using Trace-driven simulator- Evaluation Matrix : Hit Rate, Performance

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Results

Not bad about Hit Ratio with CAVE compared with Conventional Method

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Results

Good Performance with CAVE compared to Conventional Method

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Results

w/o CAVE was evaluated with Multi-channel FTL w/o CAVE with Page LRU result is not 100%, it is approximately 100%

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Summary This paper focus on exploiting full I/O parallelism.

CAVE scheme can reduce it by 55.5%-97.4% in block-level LRU using SYSMARK compared to the conventional method.