Outline for today

1. Outline for today • Topic: MEMStore paper • Administrative: • No class on Wednesday!

2. MEMS-based Storage David Nagle, Greg, Ganger, Steve Schlosser, and John Griffin http://www.chips.ece.cmu.edu/

3. What if a “disk drive” could … • Storage 10 Gbytes of data • In the size of a penny • Deliver 100 MB – 1 GB/sec bandwidth • Deliver access times 10X faster than today’s drives • Consume ~100X less power than low-power disk drives • Integrate storage, RAM, and processing on the same die • The drive is the computer • Cost less than $10 http://www.chips.ece.cmu.edu

4. How do you put a “Disk Drive” on a chip? • Build storage using MEMS • MEMS are MicroElectricMechanicalSystems • Physical sensor and actuator systems with features measured in microns • Built using process technologies similar to current CMOS fabs • Enable co-location of nonvolatile storage, RAM and processing on same physical chip http://www.chips.ece.cmu.edu

5. Example • The world's smallest guitar is 10 micrometers long – • about the size of a single cell -- with six strings each about 50 nanometers, or 100 atoms, wide. Made by Cornell University researchers from crystalline silicon, it demonstrates a new technology for a new generation of electromechanical devices. Photo by D. Carr and H. Craighead, Cornell.The above image (508 x 327 pixels) is the digital image created by the electron microscope, and is the highest-resolution version available. http://www.chips.ece.cmu.edu

6. Applications of MEMS • Sensors • accelerometers • gyroscopes • Actuators • micromirror arrays for LCD projectors • heads for inkjet printers • optical switches • microfluidic pumps for delivering medicine http://www.chips.ece.cmu.edu

7. Read/Write tips Actuators Magnetic Media MEMS-based Storage • On-chip Magnetic Storage - using MEMS for media positioning http://www.chips.ece.cmu.edu

8. Bits stored underneath each tip MEMS-based Storage Read/write tips Media side view http://www.chips.ece.cmu.edu

9. MEMS-based Storage • Read/write probe tips 1 m probe tip group of six tips 100 m http://www.chips.ece.cmu.edu

10. Y X MEMS-based Storage Media Sled http://www.chips.ece.cmu.edu

11. Y X MEMS-based Storage Springs Springs Springs Springs http://www.chips.ece.cmu.edu

12. Y X MEMS-based Storage Anchor Anchor Anchors attach the springs to the chip. Anchor Anchor http://www.chips.ece.cmu.edu

13. Y X MEMS-based Storage Sled is free to move http://www.chips.ece.cmu.edu

14. Y X MEMS-based Storage Sled is free to move http://www.chips.ece.cmu.edu

15. Y X MEMS-based Storage Springs pull sled toward center http://www.chips.ece.cmu.edu

16. Y X MEMS-based Storage Springs pull sled toward center http://www.chips.ece.cmu.edu

17. Y X MEMS-based Storage Actuator Actuators pull sled in both dimensions Actuator Actuator Actuator http://www.chips.ece.cmu.edu

18. Y X MEMS-based Storage Actuators pull sled in both dimensions http://www.chips.ece.cmu.edu

19. Y X MEMS-based Storage Actuators pull sled in both dimensions http://www.chips.ece.cmu.edu

20. Y X MEMS-based Storage Actuators pull sled in both dimensions http://www.chips.ece.cmu.edu

21. Y X MEMS-based Storage Actuators pull sled in both dimensions http://www.chips.ece.cmu.edu

22. Y X MEMS-based Storage Probe tip Probe tips are fixed Probe tip http://www.chips.ece.cmu.edu

23. Y X MEMS-based Storage Probe tips are fixed http://www.chips.ece.cmu.edu

24. One probe tip per square Sled only moves over the area of a single square Each tip accesses data at the same relative position Y X MEMS-based Storage http://www.chips.ece.cmu.edu

25. Why Use MEMS-based Storage? Capacity @ Entry Cost • Cost ! • 10X cheaper than RAM • Lower cost-entry point than disk • $10-$30 for ~10 Gbytes • New product niches • Can be merged with DRAM & CPU(s) • Example Applications: • “throw-away” sensors / data logging systems infrastructure monitoring; e.g., bridge monitors, concrete pours, smart highways, condition-based maintenance, security systems, low-cost speaker-independent continuous speech recognition, etc. • Ubiquitous use in everyday world … every appliance will be smart, store information, and communicate 100 GB HARD DISK MEMS 10 GB 1 GB 0.1 GB DRAM CACHE RAM 0.01 GB $1 $100 $10 $1000 Entry Cost http://www.chips.ece.cmu.edu

26. Why Not EEPROM? • We have computers on a chip now - Embedded computers • Billions of embedded CPUs sold today • How are HI2PS2 different today’s “embedded computer”? • Currently nonvolatile memory is EEPROM (FLASH memory) • MEMS >> increase in nonvolatile mass memory (many GB) • EEPROM* Feature Size Scaling vs. Time: 1997 1999 2001 2003 2006 2009 NOR Cell Area (um2) 0.6 0.3 0.22 0.15 0.08 0.04 (density MB/cm2) 16 32 44 64 120 240 EEPROM cost $/MB $4 $2 $1.5 $1 $0.53 $0.27 (Best Case - no increase in fab cost / cm2) • Taking EEPROM prices as $0.27/MB --> 10GB = $2,700 • For IC-Based Storage in 2009 we predict cost ~$25 / 10GB • > 100X better than EEPROM * From Semiconductor Industries Association (SIA) Roadmap 1997 http://www.chips.ece.cmu.edu

27. Why Use MEMS-based Storage? Flash memory, 0.4 µm2 cell • Volume ! • 10 GByte/cm2 = 65 GB/in2 density (100x CD-ROM) • 30 nm x 30 nm bit size • Example Applications: • Space / satellite use - store data when not in line of site act as packet buffer for communications satellites, etc. • Human portable applications - e.g., medical implants, super PDA • Law enforcement / monitoring devices / security surveillance 100,000 10,000 3.5” Disk Drive 1000 Occupied volume [cm3] 100 10 Chip-sized data storage @ 10 GByte/cm2 1 0.1 0.1 1 10 100 1000 10,000 Storage Capacity [GByte] http://www.chips.ece.cmu.edu

28. Why Use MEMS-based Storage? • Lower Data Latency ! • Conventional disk drives: worst-case rotational latency 5-11ms • IC-Based Mass Storage: depends on design - 100’s of ms possible • Example Applications • Transaction-processing storage, Non-volatile storage hierarchies, network-buffers $300 / GB EEPROM (Flash) DRAM $100 / GB Prediction 2008 $30 / GB Cost $ / GB $10 / GB MEMS Worst-Case Access Time (Rotational Latency) $3 / GB HARD DISK $1 / GB 100µs 10ns 1µs 10ms http://www.chips.ece.cmu.edu

29. 2500 2500 Media area divided into “regions” Sector is 8 data bytes + ECC + servo Data stored in “sectors” of ~100 bits ManagingMEMS-based Storage • MEMS Data Layout http://www.chips.ece.cmu.edu

30. Data layout • Optimized for: • Sequential access • Local access … 2500 1 2 3 • Serpentine layout http://www.chips.ece.cmu.edu

31. 1 2 3 … 2500 Read-modify-write example http://www.chips.ece.cmu.edu

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40. Fast Read-Modify-Write • Disks must wait an entire disk rotation to perform a read-modify-write • MEMS devices can quickly turn around and write (or rewrite a sector) • Example: Read-modify-write of 8 sectors (4KBytes) in msecs Atlas 10K MEMS Read 0.14 0.13 Reposition 5.98 0.07 Write 0.14 0.13 Total 6.26 0.33 http://www.chips.ece.cmu.edu

41. Oscillations in Y Oscillations in X X-dimension Settling Time • Consider a simple seek ... ... ... Why do we only care about the X dimension? ... Sweep area of one probe tip http://www.chips.ece.cmu.edu

42. In Y, the oscillations appear as slight variations in velocity, which can be tolerated. Oscillations in X lead to off-track interference! Sled is moving in Y X-dimension Settling Time Why do we only care about the X dimension? http://www.chips.ece.cmu.edu

43. Seek Time from Center 0.7 0.6 0.5 Seek time (ms) 0.4 0.3 0.2 0.1 0 -1000 -500 0 500 1000 X displacement (bits) http://www.chips.ece.cmu.edu

44. Seek Time from Center http://www.chips.ece.cmu.edu

45. Seek time in X Seek time in Y The Effect of Settle Time 0.7 with settling constant without settling constant 0.6 0.5 Seek time (ms) 0.4 0.3 0.2 0.1 0 -1000 -500 0 500 1000 Displacement (bits) http://www.chips.ece.cmu.edu

46. Seek Time Without Settle http://www.chips.ece.cmu.edu

47. Turn-around Access data and then turn aroundand access same data http://www.chips.ece.cmu.edu

48. Turn-around Access data and then turn aroundand access same data http://www.chips.ece.cmu.edu

49. Turn-around Access data and then turn aroundand access same data http://www.chips.ece.cmu.edu

50. Turn-around Access data and then turn aroundand access same data Turning “Turn-around”, No data is accessed http://www.chips.ece.cmu.edu