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Hybrid Hard Drives with Hybrid Hard Drives with Non-Volatile Flash and LonghornNon-Volatile Flash and Longhorn
Jack CreaseyProgram ManagerHardware Innovation [email protected] 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.