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Outline for today. Topic: MEMStore paper Administrative: No class on Wednesday!. MEMS-based Storage. David Nagle, Greg, Ganger, Steve Schlosser, and John Griffin http://www.chips.ece.cmu.edu/. What if a “disk drive” could …. Storage 10 Gbytes of data In the size of a penny

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Outline for today

Outline for today

  • Topic: MEMStore paper

  • Administrative:

    • No class on Wednesday!


Mems based storage

MEMS-based Storage

David Nagle, Greg, Ganger, Steve Schlosser, and John Griffin

http://www.chips.ece.cmu.edu/


What if a disk drive could

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


How do you put a disk drive on a chip

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


Example

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


Applications of mems

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


Mems based storage1

Read/Write

tips

Actuators

Magnetic

Media

MEMS-based Storage

  • On-chip Magnetic Storage - using MEMS for media positioning

http://www.chips.ece.cmu.edu


Mems based storage2

Bits stored

underneath

each tip

MEMS-based Storage

Read/write

tips

Media

side view

http://www.chips.ece.cmu.edu


Mems based storage3

MEMS-based Storage

  • Read/write probe tips

1 m

probe tip

group of six tips

100 m

http://www.chips.ece.cmu.edu


Mems based storage4

Y

X

MEMS-based Storage

Media Sled

http://www.chips.ece.cmu.edu


Mems based storage5

Y

X

MEMS-based Storage

Springs

Springs

Springs

Springs

http://www.chips.ece.cmu.edu


Mems based storage6

Y

X

MEMS-based Storage

Anchor

Anchor

Anchors attach

the springs to

the chip.

Anchor

Anchor

http://www.chips.ece.cmu.edu


Mems based storage7

Y

X

MEMS-based Storage

Sled is free

to move

http://www.chips.ece.cmu.edu


Mems based storage8

Y

X

MEMS-based Storage

Sled is free

to move

http://www.chips.ece.cmu.edu


Mems based storage9

Y

X

MEMS-based Storage

Springs pull

sled toward

center

http://www.chips.ece.cmu.edu


Mems based storage10

Y

X

MEMS-based Storage

Springs pull

sled toward

center

http://www.chips.ece.cmu.edu


Mems based storage11

Y

X

MEMS-based Storage

Actuator

Actuators pull

sled in both

dimensions

Actuator

Actuator

Actuator

http://www.chips.ece.cmu.edu


Mems based storage12

Y

X

MEMS-based Storage

Actuators pull

sled in both

dimensions

http://www.chips.ece.cmu.edu


Mems based storage13

Y

X

MEMS-based Storage

Actuators pull

sled in both

dimensions

http://www.chips.ece.cmu.edu


Mems based storage14

Y

X

MEMS-based Storage

Actuators pull

sled in both

dimensions

http://www.chips.ece.cmu.edu


Mems based storage15

Y

X

MEMS-based Storage

Actuators pull

sled in both

dimensions

http://www.chips.ece.cmu.edu


Mems based storage16

Y

X

MEMS-based Storage

Probe tip

Probe tips

are fixed

Probe tip

http://www.chips.ece.cmu.edu


Mems based storage17

Y

X

MEMS-based Storage

Probe tips

are fixed

http://www.chips.ece.cmu.edu


Mems based storage18

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


Why use mems based storage

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


Why not eeprom

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:

    199719992001200320062009

    NOR Cell Area (um2) 0.60.30.220.150.080.04 (density MB/cm2)16 32 44 64120240

    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


Why use mems based storage1

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


Why use mems based storage2

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


Managing mems based storage

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


Data layout

Data layout

  • Optimized for:

    • Sequential access

    • Local access

2500

1

2

3

  • Serpentine layout

http://www.chips.ece.cmu.edu


Outline for today

1

2

3

2500

Read-modify-write

example

http://www.chips.ece.cmu.edu


Outline for today

http://www.chips.ece.cmu.edu


Outline for today

http://www.chips.ece.cmu.edu


Outline for today

http://www.chips.ece.cmu.edu


Outline for today

http://www.chips.ece.cmu.edu


Outline for today

http://www.chips.ece.cmu.edu


Outline for today

http://www.chips.ece.cmu.edu


Outline for today

http://www.chips.ece.cmu.edu


Outline for today

http://www.chips.ece.cmu.edu


Fast read modify write

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 10KMEMS

      Read0.140.13

      Reposition5.980.07

      Write0.140.13

      Total6.260.33

http://www.chips.ece.cmu.edu


X dimension settling time

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


X dimension settling time1

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


Seek time from center

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


Seek time from center1

Seek Time from Center

http://www.chips.ece.cmu.edu


The effect of settle time

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


Seek time without settle

Seek Time Without Settle

http://www.chips.ece.cmu.edu


Outline for today

Turn-around

Access data and then turn aroundand access same data

http://www.chips.ece.cmu.edu


Outline for today

Turn-around

Access data and then turn aroundand access same data

http://www.chips.ece.cmu.edu


Outline for today

Turn-around

Access data and then turn aroundand access same data

http://www.chips.ece.cmu.edu


Outline for today

Turn-around

Access data and then turn aroundand access same data

Turning

“Turn-around”,

No data is accessed

http://www.chips.ece.cmu.edu


Outline for today

Turn-around

Access data and then turn aroundand access same data

http://www.chips.ece.cmu.edu


Outline for today

Turn-around

Access data and then turn aroundand access same data

http://www.chips.ece.cmu.edu


Outline for today

Turn-around

Access data and then turn aroundand access same data

Turning

“Turn-around”,

No data is accessed

http://www.chips.ece.cmu.edu


Os view of mems based storage

OS view of MEMS-based storage

  • High-level MEMS characteristics:

    • Long positioning times

    • High streaming rate

  • Logical block interface works well

    • Opportunities for device optimization, but convoluted tricks not necessary

http://www.chips.ece.cmu.edu


Fast 2004 paper

FAST 2004 Paper

  • Specificity test – are the benefits of a policy or role MEMS-specific?

    • If fails (performance same when compared to fast disk),MEMStore considered just like a fast disk wrt this role or policy

  • Merit test

    • If MEMS-specific, is it worth it (>10% improvement)?

  • Standard Storage Interface (interoperability)

    • Linear array of logical blocks (512 bytes)

    • Exact mapping of LBN to physical media is hidden

  • Contract for the Standard Interface (performance model)

    • Sequential access is best

    • Access to nearby LBN is more efficient that distant

    • Ranges of LBN are interchangeable

  • Good qualitative arguments for MEMStores to be block-oriented and the contract stays valid


Request scheduling

-MAX

0

MAX

Request scheduling

http://www.chips.ece.cmu.edu


Request scheduling1

Request scheduling

Seek time in X

Seek time in Y

-MAX

0

MAX

http://www.chips.ece.cmu.edu


Substituting migrating in disk array

Substituting/Migrating in Disk Array


Mems scheduling

MEMS scheduling

(first come, first served)

Saturation point

http://www.chips.ece.cmu.edu


Mems scheduling1

MEMS scheduling

(shortest “seek time” first)

http://www.chips.ece.cmu.edu


Mems scheduling2

MEMS scheduling

(shortest positioning time)

http://www.chips.ece.cmu.edu


Disk scheduling

Disk scheduling

Curves saturate

in same order,

relative position

X-axis shift

http://www.chips.ece.cmu.edu


Fast 2004 scheduling results

FAST 2004 Scheduling Results

SDF isShortestDistanceFirst


Data layout1

Data layout

  • Basically as for disks

    • Sequential access >>> not sequential

    • Local access > not local

  • Some interesting differences

    • File size vs. physical location

http://www.chips.ece.cmu.edu


Small requests

0.37 ms/move

in this subregion

0.42 ms/move

in this subregion

Small requests

http://www.chips.ece.cmu.edu


Large requests 256kb

0

MAX

Large requests: 256KB

  • Transfer time dominates positioning time

Long seek

Short seek

http://www.chips.ece.cmu.edu


Bipartite layout

Bipartite layout

Metadata or

small objects

Large/streaming objects

http://www.chips.ece.cmu.edu


Fast 2004 memstore specific features

FAST 2004: MEMStore Specific Features

  • Tip – subset parallelism

  • 2D data structures

  • Quick turnarounds (read-modify-write operations)

  • Device scan

2D Data Structure Accesses


Failure management

Failure Management

  • MEMS devices will have internal failures

    • Tips will break during fabrication/assembly … and during use

    • Media can wear

  • With multiple tips, data and ECC can be striped across the tips

    • ECC can be both horizontal and vertical

    • On tip or tip-media failure, ECC prevents data loss

    • Could then use spares to regain original level of reliability

http://www.chips.ece.cmu.edu


Failure management1

Failure Management

  • MEMS devices will have internal failures

    • Tips will break during fabrication/assembly … and during use

    • Media can wear

Probe Tip

http://www.chips.ece.cmu.edu


Failure management2

Spare Tip

Failure Management

  • MEMS devices will have internal failures

    • Tips will break during fabrication/assembly … and during use

    • Media can wear

Probe Tip

Spare Tip

http://www.chips.ece.cmu.edu


Failure management3

Spare Tip

Failure Management

  • MEMS devices will have internal failures

    • Tips will break during fabrication/assembly … and during use

    • Media can wear

Probe Tip

Spare Tip

http://www.chips.ece.cmu.edu


Mems in computer systems

MEMS in Computer Systems

  • MEMS-based storage device simulator

    • Uses first-order mechanics

  • Integrated into DiskSim

    • Models events, busses, cache

    • Compare against simulated disks

  • SimOS-Alpha

    • Full machine simulator with DiskSim as storage subsystem

http://www.chips.ece.cmu.edu


Random workload 15x speedup

Random Workload - 15X Speedup

10,000 small random requests, 67% reads,

exponentially sized with mean 4KB.

10,000 small random requests, 67% reads,

exponentially sized with mean 4KB.

http://www.chips.ece.cmu.edu


Random workload 15x speedup1

MEMS has small

positioning variability

Random Workload - 15X Speedup

10,000 small random requests, 67% reads,

exponentially sized with mean 4KB.

http://www.chips.ece.cmu.edu


Postmark 5x speedup

PostMark - 5X Speedup

http://www.chips.ece.cmu.edu


Mems based storage as disk cache

HP Cello trace

has 8 disks

10.4GB total capacity

Baseline MEMS

3 GB

1999 Disk

(Quantum Atlas 10K)

9 GB

MEMS-based Storage as Disk Cache

File System

MEMS

Cache

Disk

http://www.chips.ece.cmu.edu


Baseline configuration

Baseline Configuration

File System

Disk

Disk

Disk

Disk

http://www.chips.ece.cmu.edu


Disk cache configuration

Disk Cache Configuration

File System

MEMS

MEMS

MEMS

MEMS

http://www.chips.ece.cmu.edu


Disk cache configuration1

MEMS

Cache

MEMS

Cache

MEMS

Cache

MEMS

Cache

Disk

Disk

Disk

Disk

Disk Cache Configuration

File System

http://www.chips.ece.cmu.edu


Mems based storage as a disk cache

MEMS-based Storage As a Disk Cache

http://www.chips.ece.cmu.edu


File system managed layout

File System-managed Layout

  • File system could allocate data directly

File system

Disk

MEMS

  • Metadata

  • Small files

  • Paging

  • Large, streaming files

http://www.chips.ece.cmu.edu


Low power disk drives

Low-power Disk Drives

  • IBM Travelstar 8GS

Command stream ends

3

Active

2

Power (W)

Perf Idle

40 ms

1

400 ms

2 s

Fast

Idle

Low power Idle

Standby

0

0

5

10

Time (s)

http://www.chips.ece.cmu.edu


Mems based storage19

Standby

(not to scale)

1

Active

Power (W)

0

0

5

10

Time (s)

MEMS-based Storage

  • Lower operating power

    • 100 mW for sled positioning

    • 1 mW per active tip

    • For 1000 active tips, total power is 1.1 watt

    • 50 mW standby mode

  • Fast transition from standby

0.5 ms

http://www.chips.ece.cmu.edu


Postmark

PostMark

3111

58

http://www.chips.ece.cmu.edu


Postmark1

PostMark

Performance Idle

Active

Active

http://www.chips.ece.cmu.edu


Netscape

Netscape

6097

349

http://www.chips.ece.cmu.edu


Netscape1

Netscape

Lots of transitions

Largely idle

Active

http://www.chips.ece.cmu.edu


Future of mems based storage

Future of MEMS-based Storage

  • Perfect for portable devices

    • Size, capacity, power

http://www.chips.ece.cmu.edu


Mems based storage is on the way

MEMS-based Storage Is On the Way

  • Interesting new storage technology

    • Gigabytes of non-volatile data in a single IC

    • Sub-millisecond average access time

    • Low power

  • Can fill various roles

    • Augment memory hierarchy

    • Portable devices

    • Archival storage

    • Active storage devices

http://www.chips.ece.cmu.edu


Mems based storage at cmu

MEMS-based Storage at CMU

lcs.web.cmu.edu/research/MEMS

[email protected]

http://www.chips.ece.cmu.edu


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