Hybrid Hard Drives with Hybrid Hard Drives with Non-Volatile Flash and LonghornNon-Volatile Flash and Longhorn

Jack CreaseyProgram ManagerHardware Innovation GroupMSHybrid@Microsoft.comMicrosoft Corporation

Demo Introduction

Hybrid Hard Disk Architecture

Power Savings using NV Cache

Demo Results (Power saving)

Faster Boot and Resume Process

Demo (Boot and Resume)

System Design with the Hybrid Hard Disk

Other Design Approaches

Next Steps

Session OutlineSession Outline

Session GoalsSession Goals

Attendees should leave this session with the following:

An understanding of the power savings that can be achieved using Hybrid Hard Disk technology

An understanding of the boot and resume efficiencies that can be achieved using Hybrid Hard Disk with Windows codenamed “Longhorn”

An understanding of the increase in MTBF expected from a Hybrid Hard Disk

Knowledge of where to find resources to aid in system design using the Hybrid Hard Disk

Storage Devices: Key Windows StrategiesStorage Devices: Key Windows Strategies

Optical Platform Client/Consumer

Storage Fabrics Server/Enterprise

Personal Storage Client/Consumer

Preferred Storage Platform

Partner/Customer

Timely, comprehensive, quality platform support for optical devices

Optimized platform features enabling new customer scenarios in Personal Storage

Leading platform supporting storage fabrics

Preferred platform for developing, Preferred platform for developing, integrating, and deploying storage devices integrating, and deploying storage devices

DemoDemo

Power Savings

Why Change the Disk Drive?Why Change the Disk Drive?

Consumes 10-15% of the power budget in mobile solutions

Slow power up Spin up times can be 2-5 seconds

Seek and rotational latency is a performance bottleneck

Fragile, shock prone, low MTBF in mobile systems

Most common failure point in mobile solutions

Failure may result in user data loss

What is a Hybrid Disk Drive?What is a Hybrid Disk Drive?

DramCache

NVCache

Add a non-volatile cache

ATA Interface

Why is a Hybrid Hard Disk Better?Why is a Hybrid Hard Disk Better?

Reduce Power ConsumptionRead and Write disk data while drive is in a low power state with the spindle stopped

Faster Boot and ResumeInstant access to data in NV Cache

Higher ReliabilityBetter shock resistance

Lower operating duty cycle

Hybrid Disk Drive BenefitsHybrid Disk Drive Benefits

DramCache

NVCache

Up to 90% Power Savingwhen powered down

ATA Interface

Read and Write instantly while spindle stopped

Technical Assumptions for Hybrid DiskTechnical Assumptions for Hybrid Disk

Longhorn* with its advanced memory management is the optimal for caching read data (but not write data)

The Hybrid Hard Disk NV Cache is the optimal location for write data

NV Cache should be >= 64MB and we recommend 128MB

Longhorn* will be able to define data (LBAs) to be Pinned in the NV Cache for Boot and Resume benefits

* Planned for Longhorn Beta 2

Flash Buffer Size for Power ReductionFlash Buffer Size for Power Reduction

Field data from Windows XP-based PCs

Preliminary results:>9,000,000 10min “active use” intervals

93% of 10min active use intervals < 64MB unique data written

Unique MB Written on Battery(10 Min Interval)

0

200

400

600

800

1000

1200

1400

1600

0 8 16

24

32

40

48

56

64

72

80

88

96

104

112

120

128

136

144

152

160

168

176

184

192

Mo

re

Size (MB)

Fre

qu

en

cy

0.00%

20.00%

40.00%

60.00%

80.00%

100.00%

120.00%

Frequency Cumulative %

Power Saving ModePower Saving Mode

Windows memory management buffers disk data in System DRAM which fulfills reads

Windows puts the HDD into NV Cache mode which spins-down the disk spindle and results in write (and read) IOs to the NV Cache

Upon NV cache miss or the NV Cache filling the spindle is spun-up to satisfy reads and flush write data to magnetic media

The disk spins-down and continues to use the NV Cache

2.5” HDD

Hard DiskController

64-128MBNV Cache

Motherboard

DRAM

ATA Controller

Windows Longhorn

Power SavingPower Saving

80% reduction in power can be achieved (from 1.2W to 0.24W)Assumptions

Pavg active = 1.2W (measured)Pavg with Flash write buffer and “Longhorn” kernel = 0.18W (calculated)

Toff = 600s @ .18WTon = 15s @ 2.5W

Ton = spin-up time (2s) + Flash buffer flush time (13s)Flash buffer size = 128MBTransfer rate = 10MB/sPavg = ( 600*0.18 + 15*2.5 )/615 = 0.24W

Pow

er (

W)

Time

1.5

1

0.5Pavg with flash write buffer = .24W

Toff > 600s

onPavg with disk spindle and seek in use = 1.2W T 15s

Power reduced 0.76W

Demo ResultsDemo Results

View disk spindown times

Cold Boot ProcessCold Boot Process

BIOS runs POST

Initializes the disk drive

Reads partition table from disk

Reads first logical block from bootable volume

Reads NTLDR which executes and loads Windows

Hybrid Disk Boot and ResumeHybrid Disk Boot and Resume

During shutdown or hibernate all the disk sectors needed to boot or resume are pinned into the NV cacheOn next power on the BIOS POST runs and the disk is powered on but the spindle won’t be ready for 2-5 secondsBIOS can read data from the NV cache and all boot process IO can be satisfied immediatelyOnce booted or resumed, Longhorn memory management fills system memory with most used disk dataWindows puts the HDD into NV Cache mode which spins-down the disk and results in write and read IOs to the NV CacheUpon NV cache Read miss or the NV cache filling, the spindle is spun-up to satisfy Reads and flush cached write data to diskThe disk spins-down and continues to use the NV cache

2.5” HDD

Hard DiskController

64-128MBNV Cache

Motherboard

DRAM

ATA Controller

Windows Longhorn

DemoDemo

Suspend/resume

System Design with Hybrid Hard DiskSystem Design with Hybrid Hard Disk

Design objective: Enable fast boot/resume and save power

Standard motherboard ATA Interface

BIOS must exit POST rapidlyFast memory check

Fast Chipset initialization

Initialize HDD early

BIOS must pass to boot loader quicklyFast PNP detection

Boot HDD first in boot order

Main memory => 512MB

Other Design Approaches ConsideredOther Design Approaches Considered

Flash memory device on the MotherboardPotential corruption if cache and disk separated

Only provides partial functionality and requires significant additional design changes

Requires new disk driver that owns pinning and cache management

BIOS must be able to resolve cache/disk mapping before a driver loads

Flash memory and Hybrid disk controller on Motherboard

Potential corruption if controller and disk separated

Double processes all commands to the disk subsystem

Higher cost structure (additional ASIC)

HDD PartnersHDD Partners

Samsung Electronics – Semiconductor Division Flash product planning team worked with Microsoft on specification of the ATA command set Samsung Semiconductor, together with Seoul National University (SNU) developed the “proof of concept” prototype Hybrid Hard Drive emulatorSamsung Electronics has started to develop commercial Hybrid Hard Disk drives

HitachiWorked with Microsoft on specification of the ATA command setProvided feedback on Hybrid Hard Disk power, boot and MTBF models

SeagateWorked with Microsoft on specification of the ATA command set

Community ResourcesCommunity Resources

Windows Hardware & Driver Central (WHDC)www.microsoft.com/whdc/default.mspx

Technical Communitieswww.microsoft.com/communities/products/default.mspx

Non-Microsoft Community Siteswww.microsoft.com/communities/related/default.mspx

Microsoft Public Newsgroupswww.microsoft.com/communities/newsgroups

Technical Chats and Webcastswww.microsoft.com/communities/chats/default.mspx

www.microsoft.com/webcasts

Microsoft Blogswww.microsoft.com/communities/blogs

Relevant Mobile Platforms Relevant Mobile Platforms PresentationsPresentations

TWDT05010Building a Longhorn-Ready Mobile PC

TWAR05001Longhorn Power Management Update

TWAR05002System Performance Assessment Tools For Windows Longhorn

Call To ActionCall To Action

HDD manufacturers should contact Microsoft for information on Hybrid Hard Disk support in Windows OS

Implementation WhitepaperATA Command Set

OEMs Contact Hybrid Hard Disk Partners to plan OEM certification processOEMs need to include testing on Hybrid disk functionality at Longhorn Beta Two release

Contact MSHybrid @ Microsoft.com with any questions.