Sungkyunkwan University

Sector Level Mappinng #1

Computer engineering , Sungkyunkwan Univ.

Oh Gihwan, Han Gyuhwa , Hong Gyeonghwan

Jasmine Open-SSD Project Tuto-rial2- Sector Level Mapping FTL

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Index

Sector Level Mapping

Write module for sector level mapping

Read module for sector level mapping

Considerations

Experiments

Conclusion

Reference

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Sector Level MappingLSN PSN

<W, 100, 10><W, 2, 20><R, 3, 10>

<W, 100, 20>..

<W, 20, 60>

..........................

..........................

Flash Memory Page

Sector MappingTable

Merge Buffer

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Write module for sector level mapping ( 1/3 )

LSN PSN100 0x80...101 0x80...

.....20 0x80...21 0x80...22 0x80...

<W, 100, 10><W, 2, 20>

<W, 100, 20>..

<W, 20, 60>

100 101 ............. 21 22.............

..........................

Flash Memory Page

Merge Buffer

Sector MappingTable

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Write module for sector level mapping ( 2/3 )

LSN PSN100 0x80...101 0x80...

.....20 0x80...21 0x80...22 0x80...

<W, 100, 10><W, 2, 20>

<W, 100, 20>..

<W, 20, 60> 21 .............22 .............

Flash Memory Page

Merge Buffer

100 .............101 .............

Sector MappingTable

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Write module for sector level mapping ( 2/3 )

LSN PSN100 0x80...101 0x80...

.....20 0x80...21 0x80...22 0x80...

<W, 100, 10><W, 2, 20><R, 3, 10>

<W, 100, 20>..

<W, 20, 60>..........................

Flash Memory Page

Merge Buffer

100 101 ............. 21 22.............

Sector MappingTable

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Write module for sector level mapping ( 3/3 )

LSN PSN100 0x00...101 0x00...

.....20 0x00...21 0x00...22 0x00...

<W, 100, 10><W, 2, 20><R, 3, 10>

<W, 100, 20>..

<W, 20, 60>

..........................

..........................

100 101 ........

21 22

Flash Memory Page

Merge Buffer

Sector MappingTable

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Read module for sector level mapping

LSN PSN100 0x80...101 0x80...

.....20 0x00...21 0x00...22 0x00...

<R, 100, 10><R, 2, 20><R, 3, 10>

<R, 100, 20>..

<R, 20, 60>

100 101 .............

.............

..........................

2 3 ........

21 22

Flash Memory Page

Merge Buffer

Sector MappingTable

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Considerations

보고서의 구현 이슈 부분

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Experiments

Environment Application : Iometer

– Random test : 512 Bytes, 1 KB , 2KB , 4KB – Sequential test : 128 KB

ATTO– Queue depth : 10 – Transfer size : 512Bytes ~ 32KB

FTL Tutorial Greedy Static Sector mapping Dynamic Sector mapping 1 buffer Sector mapping Multi copy Sector mapping

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Experiments results ( 표 )

Random Write test ( Average of four tests )

Sequential Read/Write test ( Average of four tests )

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Experiments results ( 그래프 )

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Experiments results

실험 분석

실험 결과가 저렇게 나온 이유

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Conclusion

개선 사항 ( 할 수 있다면 GC 개선 , Table 관리 정책 ,

불필요한 변수들 최적화 , 알고리즘을 적용한 여러가지 트릭

)

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Reference

DFTL: a flash translation layer employing demand-based selec-

tive caching of page-leve address mappings / 저자 : Aayush

GuptaKim, Bhuvan UrgaonkarYoungjae

OpenSSD Project - www.openssd-project.org.

The Jasmine OpenSSD Platform: FTL Developer's Guide –

http://www.openssd-project.org/

The Jasmine OpenSSD Platform: Technical Reference Manual

- http://www.openssd-project.org/

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Q & A