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Love/Hate Relationship between Flash
 Memory and Microdrive for Low-Power
 Portable Storage

                             ...
Portable Storage Applications




 Source: http://www.samsung.com/AboutSAMSUNG/InvestorRelations/ IREvents/downloads/2003_...
Cost Comparison
                                                                                                  $399.95 ...
FTL (Flash Translation Layer)
  Definition
     Software layer that makes flash memory appear to the system like
     a di...
Block level mapping
 Logical blocks
                0   1                                                              N -...
Read procedure
 Ex. read 3 sectors from 255
                             Logical blocks



       …              …        ...
Write procedure (Map block update)
  Ex. write 3 sectors from 255
        …                  …             …              ...
Host Interface Performance
Transfer Rate (MB/s)
     800                                                                  ...
HDD Internal Data Rate




Source: http://www.hitachigst.com/hdd/technolo/overview/chart16.html
                          ...
Flash Chip Bandwidth
     Write bandwidth = 2KB/300us = 6.7MB/s per chip
     Read bandwidth = 2KB/25us = 80MB/s per chip
...
21




Agenda
 Overview of Portable Storage Technologies
 Techniques for High Performance
 Techniques for Low Power
 Concl...
Techniques for High Performance
 Flash Drive

                             CPU
                                           ...
Agenda
  Overview of Mobile Storage Technologies
  Techniques for High Performance
  Techniques for Low Power
  Conclusion...
The Love Part: HDD+Flash Combo



                                                                                   HDD w...
HDD+Flash Combo Block Diagram


                            CPU
                                                    SRAM
 ...
Key Considerations
1.   Correctness: should preserve the semantics of HDD
2.   Fault tolerance and graceful degradation: s...
Conclusions
     In the animal world
           Survival of the fittest




     In the memory world
           Survival o...
The Ultimate Limit – Micro Drive



    Fly      2,000,000 Miles Per Hour
     By
    Night
                            Bo...
Announcement
 IWSSPS 2005: International Workshop on Software
 Support for Portable Storage
 Date: March 6, 2005
 Place: S...
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Microsoft PowerPoint - PRAC2004

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Transcript of "Microsoft PowerPoint - PRAC2004"

  1. 1. Love/Hate Relationship between Flash Memory and Microdrive for Low-Power Portable Storage 2004. 09. 26 Sang Lyul Min Seoul National University & Samsung Electronics Agenda Overview of Portable Storage Technologies Techniques for High Performance Techniques for Low Power Conclusions 2
  2. 2. Portable Storage Applications Source: http://www.samsung.com/AboutSAMSUNG/InvestorRelations/ IREvents/downloads/2003_samsungforum.pdf 3 The Contenders for Portable Storage Market Flash Drive Micro Drive IBM Hitachi Samsung Toshiba Hitachi Seagate Portable Storage SanDisk LexarMedia 4
  3. 3. Cost Comparison $399.95 (2004.8) $299.88 (2004.8) $259.88 (2004.8) Source: http://www.hitachigst.com/hdd/technolo/overview/chart03.html 5 NAND Flash Memory Basics 2j blocks Data Spare Data Spare Data Spare Data Spare Data Spare Data Spare Data Spare Data Spare Data Spare 2i ……… pages … … … Data Spare Data Spare Data Spare Read physical page Erase block (chip #, block #, page #) (chip#, block #) ~ 25 us ~ 2 ms Write physical page (chip #, block #, page #) ~ 300 us 6
  4. 4. FTL (Flash Translation Layer) Definition Software layer that makes flash memory appear to the system like a disk drive Challenges in FTL Asymmetry in read and write speeds No overwrite is allowed without erasing 7 Logical interface for a disk drive 512B 512B … 512B 0 1 N -1 Operations 1. Identify drive(): returns N 2. Read sectors(start sector #, # of sectors) 3. Write sectors(start sector #, # of sectors) 8
  5. 5. Block level mapping Logical blocks 0 1 N -1 Sectors … 256 sectors Logical … … … blocks 0 N / 256 9 Block level mapping Logical to physical block mapping Logical blocks Visible (data blocks) Invisible … … … … … … 0 1 L Block mapping table (map block) … … … … Physical blocks 10
  6. 6. Read procedure Ex. read 3 sectors from 255 Logical blocks … … … … … … 0 1 L Block mapping table (map block) … … … R R R … Physical blocks 11 Write procedure (Data block update) Ex. write 3 sectors from 255 … … … … … … 0 1 L Block mapping table (map block) … … … … … W W W … … Write buffer blocks Still, update of write buffer blocks for data 1. Erase mapping information is needed 2. Write data pages pages 3. Fill remaining data 12
  7. 7. Write procedure (Map block update) Ex. write 3 sectors from 255 … … … … … … 0 1 L Block mapping table (map block) … … … … … W W W … W … Write buffer blocks Still, somewhere we need to keep the addresses of 6. Read-modify-write map for map Fill remaining map pages 5. Erase and write buffer blocks (i.e., logging) 4. new mapwrite buffer blockspage 13 Inside Hard Disk Drive CPU SRAM/DRAM core System Bus USB, PCMCIA, SATA Host Interface Platters 14
  8. 8. Host Interface Performance Transfer Rate (MB/s) 800 SAS6Gbps 700 S-ATA3 600 500 IEEE SAS3Gbps 1394b 400 Ultra320 SCSI S-ATA2 300 IEEE 1394b 200 Ultra160 SCSI S-ATA1 IEEE IEEE 1394b 100 Ultra Ultra2 SCSI 1394a U-ATA66 2.0 USB SCSI-3 SCSI U-ATA33 SCSI-1 SCSI-2 ATA1 ATA2 USB 1.1 0 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 19 19 19 19 19 19 19 19 19 19 19 19 19 19 20 20 20 20 20 20 20 20 ATA SCSI SERIAL 15 HDD Form Factor and Capacity Source: http://www.hitachigst.com/hdd/technolo/overview/chart01.html 16
  9. 9. HDD Internal Data Rate Source: http://www.hitachigst.com/hdd/technolo/overview/chart16.html 17 Inside Flash Drive CPU SRAM core System Bus Flash Bus Host Flash Interface Interface USB, PCMCIA, SATA Flash Chips 18
  10. 10. Flash Chip Bandwidth Write bandwidth = 2KB/300us = 6.7MB/s per chip Read bandwidth = 2KB/25us = 80MB/s per chip Erase bandwidth = 128KB/2ms = 64MB/s per chip 19 Flash bus bandwidth picture 20~33Mb/s per Pin Flash Source: Terry Lee, Micron Technology, Inc, VTF (VIA Technology Forum) 2003 20
  11. 11. 21 Agenda Overview of Portable Storage Technologies Techniques for High Performance Techniques for Low Power Conclusions 22
  12. 12. Techniques for High Performance Flash Drive CPU SRAM core System Bus High speed Flash bus Flash Bus Host Flash Interface Interface USB, PCMCIA, etc “Sleeping with the enemy” “Getting out of the way” Flash Chips Multiple logical chips in a single packaging (multi-banking) 23 Techniques for High Performance HDD Source: http://www.hitachigst.com/hdd/technolo/overview/chart19.html 24
  13. 13. Agenda Overview of Mobile Storage Technologies Techniques for High Performance Techniques for Low Power Conclusions 25 Literature on Power Modeling of Portable Storage IBM Corporation. Adaptive Power Management for Mobile Hard Drives. Technical Report, Storage Systems Division, IBM Corporation, April 1999. Available at: http://www.almaden.ibm.com/almaden/pbwhitepaper.pdf. John Zedlewski, Sumeet Sobti, Nitin Garg, Fengzhou Zheng, Arvind Krishnamurthy, and Randolph Wang. Modeling Hard-Disk Power Consumption. Proc. Second Conference on File and Storage Technologies. March 2003. Fengzhou Zheng, Nitin Garg, Sumeet Sobti, Chi Zhang, Russell E. Joseph, Arvind Krishnamurthy, and Randolph Y. Wang. Considering the Energy Consumption of Mobile Storage Alternatives. IEEE Symposium on Modeling, Analysis and Simulation of Computer Systems. October 2003. 26
  14. 14. The Love Part: HDD+Flash Combo HDD with reduced + = power consumption and start-up time HDD NAND Flash 27 Why HDD+Flash Combo? 1. Power consumption aspects: In a laptop PC, HDD consumes ~10% (~2W) total power when disk platters are spinning ~1% (~0.2W) total power when disk platters are idle 2. Cost aspects: 128MB Flash write buffer < $8 in 2006 < $4 in 2008 3. Reliability aspects: 4. Performance aspects: Source: Clark Nicholson, “Improved Disk Drive Power Consumption Using Solid State Non-Volatile Memory”, WinHEC2004. 28
  15. 15. HDD+Flash Combo Block Diagram CPU SRAM core System Bus Flash Bus Host Flash Interface Interface SATA Flash Chip Platters 29 Key Benefits of HDD+Flash Combo 87% reduction in power can be achieved (1.75W) Assumptions Pavg active = ~2W (measured) Pavg with Flash write buffer and “Longhorn” kernel = 0.25W (calculated) Toff = 600s @ .18W Ton = 18s @ 2.5W Ton = spin up time (5s) + Flash buffer flush time (13s) Flash buffer size = 128MB Transfer rate = 10MB/s Source: Clark Nicholson, “Improved Disk Drive Power Consumption Using Solid State Non-Volatile Memory”, WinHEC2004. 30
  16. 16. Key Considerations 1. Correctness: should preserve the semantics of HDD 2. Fault tolerance and graceful degradation: should operate correctly despite partial/total failure in flash memory 3. Power efficiency: should reduce the power consumption as much as possible 4. Reliability: should improve the reliability as much as possible 5. Performance: should improve the user-perceived performance as much as possible 31 Agenda Overview of Poratble Storage Technologies Techniques for High Performance Techniques for Low Power Conclusions 32
  17. 17. Conclusions In the animal world Survival of the fittest In the memory world Survival of the fastest or cheapest ? Volatile Non-volatile Fastest SRAM FRAM? Cheapest DRAM NAND Flash HDD 33 Conclusions From the history IBM 360/85 IBM 360/91 Clock Rate 80 ns 60 ns Memory Speed 1040 ns 750 ns Memory Interleaving 4 way 8 way Register Renaming, Additional Features Cache Memory Out-of-order Execution, etc But, IBM 360/85 faster on 8 of 11 programs! Source: David Patterson, et al., “A Case for Intelligent DRAM: IRAM”, Hot Chips VIII, August, 1996 34
  18. 18. The Ultimate Limit – Micro Drive Fly 2,000,000 Miles Per Hour By Night Boeing 747 1/100” Flying Height Source: Richard Lary, The New Storage Landscape: Forces Source: shaping the storage economy, 2003. http://www.hitachigst.com/ 35 The Ultimate Limit – Flash Drive B/L Direction 200nm W/L Direction Source: K. Kim et al. IEDM Tech. Dig., 2002, pp. 919-922 36
  19. 19. Announcement IWSSPS 2005: International Workshop on Software Support for Portable Storage Date: March 6, 2005 Place: San Francisco, USA (along with IEEE RTAS 2005 and Embedded System Conference 2005) Important Dates: Paper Submission: December 15th 2004 Notification of Acceptance: January 15th 2005 Camera-ready due: February 15th 2005 37 Topics of interest include, but are not limited to: - File system for portable storage - Interaction between file system and portable storage - FTL (Flash Translation Layer) for Flash memory - Power management for HDD including microdrives - DRM (Digital Right Management) for portable storage - Distributed mobile storage - Software reliability for portable storage - Software fault tolerance techniques for portable storage 38

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