the drive interface progress cycle · embedded flash disk raw nand + hdd controller with nand...

© 2005 Hitachi Global Storage Technologies

The Drive Interface Progress Cycle

Dan Colegrove

December 6, 2005


Interface Development Cycle

New Interface Feature Development Cycle:•Development of the New Feature (Specification/Standard)

•Prototypes •First Generation Products •Refinement of Standard/Specification •Conversion to New Products / Volume Ramp•Phase Out of Older Technology •Development of Next Generation



Disk drive interface serialization was a major shift, ATA to SATA, Parallel SCSI to SAS.•SAS and SATA are not plug compatible with parallel equivalents

– Large investment by both drive manufacturers and OEMS to switch.

– Long transition •Serialization of ATA and SCSI interfaces allow new applications

– Large arrays with both SAS and SATA drives



SATA and SAS• Transition to SATA is proceeding• SAS provides support for both SAS and SATA storage arrays so it will transition

somewhat faster than SATA.

A period of stability to allow drive manufacturers and OEMs to profit from the investment in the conversion to serial.

A large jump in interface speed with SATA; SAS not as much. • SATA 133 Mbytes/s -> 300 Mbytes/s• SAS 320 Mbytes/s split over up to 15 drives to 300 Mbytes/s per drive

SATA 3 Gigabit greatly exceeds drive data rates in Desktop/Mobile• 3 Gigabit should be sufficient to beyond 2011.

SAS needs additional speed in the expander network, but not to the drive. • Enterprise class drives will not need more than 3 Gigabit until 2011• Fortunately the transition to serial and a branching expander network will allow higher

bandwidth connections to storage arrays without requiring support by individual drives


Constant Stream of New Features

Steady progress in new features and functions• ATA

– SATA Queuing – Large Physical Sector Support (4K) – AV Streaming Support

• SCSI– End to End Data Protection

• Software Support for new features takes time, but less than for a physical change. – Time dependant on the degree of OS/Driver/Application impact– Some Linked to OS releases (e. g. Windows Vista)– Prioritized by OEM and End User Interest.

1. End User Perceptible new Feature (Capacity) (AV Streaming) (SAS support for SATA) End User Perceptible Performance Increase (RPM) (SATA Queuing)

2. Cost Reduction (4K)3. Technology Change (SATA) (SAS)


Conclusion

SATA was a big change

SAS was big change

It will take time to complete the transition

There is little opportunity for a another major change until the transition to SATA and SAS is complete

New interface features will continue to be developed• Time to implementation depends on level of OS/BIOS/Driver support

required

Hybrid HDD What flash technology should be used?

By: Esther SpanjerDirector of Technical Marketing

2

Agenda

Introduction to Hybrid HDD

Requirements for NV Cache

NVM options for NV Cache

Embedded Flash Disk

Raw NAND + HDD controller with NAND support

Raw NAND + NAND controller + HDD controller

Comparing alternatives

Summary

3

Storage - looking into the future

Telecommunications

HDD

SSDTablet PC

Desktop

PVR

SAN

Rugged Laptop

Data recording

POS

Laptop

Thin Client

Blade Server

Hybrid

4

The Hybrid HDD concept

DRAMCache

NVCache

Add a non-volatile cache

ATA Interface

MicrosoftNV cache inside HDD

128MB recommended

Stores frequently used sectors for fast boot and resume

Supported in Vista

Intel (Robson cache)NV Cache on motherboardBoot OS from flashDemo’ed with 128MB

Why not large NV cache (2-4GB)?

Store critical system info: registry, favorites, etc.

5

Advantages of Hybrid Hard Disk

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

6

Requirements for NV cache

Capacity: 128MB-1GB (up to 4GB in future?)

Small size - Limited space on the HDD PCB or motherboard

Multi-source

Ease-of-integrationExisting HDD controllers support NOR interface only, not NAND

PerformanceFast read performance for fast boot and resume time

Fast write performance to reduce power consumption and fast timeto enter hibernation

No added reliability risk

Low Cost

Short TTM – playing in consumer market

7

NVM options for Hybrid HDD

Embedded Flash DiskController + flash in same package

Raw NAND + HDD controller with NAND support

Raw NAND + NAND controller

8

NAND Flash Market LandscapeFuture Flash Trends

Compromising on reliability with every new processDifferent EDC/ECC is required

Boot becomes slower and more complicated

Compromising on performance

Compromising on enduranceBetter wear-leveling is crucial

Compromising on data retentionCode storage is a challenge

Compromising on compatibilityDifferent page sizes between different vendors

Not always compatibility between processes and vendors

Managing flash becomes more complex

9

Embedded Flash Disk vs. Raw NAND

Raw NAND

Density per $ Compatibility

Page Size

PPP

MLC

8 bit EDC

# of planes

Boot support

10

Density per $ Compatibility

Embedded Flash Disk vs. Raw NAND

Embedded Flash Drives (EFD)

MLC & SLC

Any Process

Any Page Size

Any OS

Any Processor

Single Software

Boot support

11

EFD for Hybrid HDD

AdvantagesMinimal PCB space – one chip solution

Provides NOR interface, no need for new HDD controller

Software already provided by flash manufacturer better TTM

Alleviates all flash “headaches”

Multi-source (some vendors)

Best access to latest flash technology without redesigning HDD

DisadvantagesSlightly higher cost than raw NAND

12

HDD controller with NAND support

Mobile vendors chipset support for Flash

SLC

2K Page

MLC NAND

6 bit MLC

4KB Page

No Support

0.5K SLC

2K SLCSMSG MLC

2001

2002

2003

2006

2007

2004

2005

2001

2002

2003

2006

2007

2004

2005

MLC Support?

Chipsets NAND

200?

?Expected that HDD vendors will face same time gap problems

13

HDD controller with NAND support

AdvantagesLow cost for raw NAND

Minimal PCB space – one chip solution

DisadvantagesDevelopment time longer

R&D cost higher (new ASIC development)

Difficult to keep up with huge flash offering: SLC/MLC, 90/70/50nm, large/small block, different flash vendors etc

Decreasing flash geometry less reliable flash more knowledge of HDD vendor required to support

Flash management software – who to provide?

Flash chips not compatible between flash vendors no true second source

14

Raw NAND + NAND Controller

AdvantagesMulti-source flash chip NAND controller supports various NAND flashes

DisadvantagesMulti-source for NAND controller

More PCB space – 2 chip solution

Additional cost for NAND controller

Software support – who to provide?

Time gap in following latest flash technology

When using MLC flash – reliability might be compromised

15

Comparing Alternatives

Raw NAND+

NAND controller

Embedded Flash Disk

Raw NAND+

HDD controller

Footprint 2 chip solution 1 chip solution 1 chip solution

Multi source Limited Yes Very limited

Ease-of-Integration

Hard Easy Very Hard

Flash Endurance Low High Low

Performance Medium Fast Medium

TTM Medium Fast Slow

Support for best flash

No Yes No

TCO Medium Best Medium

Reliability Medium High Low

16

Summary

We’re at crossroads in storage industryWho will dominate? HDD, SSD, Hybrid HDD?

First prototypes Hybrid HDD demo’ed by Samsung and Intel

Flash Expertise will become criticalManaging flash is becoming more and more complex

Raw NAND has low cost, but many headaches

Embedded Flash DiskMeets the Hybrid HDD requirements for performance, reliability and ease-of-integration

Offers real multi-source solution

Small footprint

Fastest time to market

Best option to use latest flash technology without need for redesign

the drive interface progress cycle · embedded flash disk raw nand + hdd controller with nand...

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