Data Matters - A blog about flash memory

Why Raw NAND Flash with Hardware-based ECC is the Way to Go

michele — Thu, 20 Nov 2008 18:21:14 +0000

5 Reasons for Ditching Managed NAND
Everyone knows that NAND has challenges: from factory bad blocks and spontaneous bit failures to endurance limits, etc. That’s why a few years ago managed NAND (NAND flash plus an integrated controller) seemed to be the answer, offering the density of raw NAND, while mitigating many of its inherent limitations. What many device manufacturers may not realize is that the management hardware comes with significant costs, both in terms of dollars per part as well as design limitations. In the world of tradeoffs in which every system designer lives, there are solid technical reasons to consider using raw NAND and leaving the management to software instead. While there are clear commercial advantages for Datalight (as a provider of vendor-neutral software-based flash management) to advocate this approach, we also believe that there are strong technical reasons that flash silicon vendors would do well to embed ECC capabilities into their NAND flash devices rather than relying on ‘total hardware’ solutions such as eMMC or other complex and costly controllers. Beyond the benefits outline below, this approach would allow the flash manufacturers the ability to continue to differentiate their products from others in the industry.

1. Cost
The cost of managed NAND parts is coming down, but the stuff still sells at a premium over its raw NAND brethren.

2. Flash Optimization
There are many new features of NAND available to us today. Performance features such as cached reads, multi-plane operations, concurrency, and others are becoming invaluable to keep performance at the ever-increasing demands of portable media. The Open NAND Flash Interface (ONFI) has defined a standard method to query the capabilities and characteristics of NAND flash which can be put to use by both software and hardware systems. A software media manager offers the flexibility to take advantage of the most current flash memory features and put them to use efficiently, or to avoid certain features that may be unproven or problematic. A software solution will allow a developer to take full advantage of the media’s characteristics and features unburdened by the indirection or inability for the hardware to expose them.

3. Visibility/Flexibility
Software (in general) is easily inspected and validated. Features such as wear-leveling move data around the flash device to optimize its life expectancy. Without the ability to inspect source code, a managed NAND solution makes it difficult to validate wear-leveling operation and/or characterize its effect on performance and reliability. Hardware implementations are often generalized to suit a majority of use cases, while a software solution is easily tailored to the specific use case during development.

4. Performance
Speaking of use cases, there are many system features that are not available to hardware that may make a generalized hardware solution less advantageous to a specific use case. For example, system idle time can be used to improve the media performance by scheduling background cache operations and compaction to occur then. Coordination between the file system and flash media manager can further optimize operations by freeing space when it will no longer be needed and having the media manager code cache certain regions of the flash where meta data might be held. Migrating flash management features to hardware removes this ability to coordinate with other components of the software stack, such as file systems.

5. Reliability
Lest you think we believe that everything is better left to software, consider error detection and correction (EDC). Error rates are increasing substantially as flash manufacturers push the limits of physics. Errors can be introduced externally by heat or other radiation, during writes or reads of data, and even to data that was successfully written at a different time. Historically SLC NAND flash required only a single bit error detection and correction (a hamming code is usually sufficient), while MLC parts require minimally four bit EDC. As the die sizes continue to shrink, error rates will continue to increase, even for SLC flash.
Calculating the codes to detect and correct such errors is getting increasingly complex and solving such a solution in software for higher-bit EDCs (above 4-bit) is time consuming and often unacceptably slow. Hardware ECC is a necessary requirement for systems with high EDC requirements and where performance is a concern.

Many of the processors on the market today are incorporating EDC in their NAND controllers. Choosing one of these processors (e.g. TI OMAP 35xx) in combination with raw NAND flash and software management can give you the high-performance EDC to handle next generation flash while maintaining the design flexibility that a software manager provides.

Flash manufacturers have much to gain by adding ECC code into their NAND flash parts. They know better than anyone what kind of ECC is necessary for a specific part and by adding just that one piece of hardware to their offerings, rather than the jack of all trades, master of none approach of complete flash management, they will better serve the markets.

In short, features should reside where they can be handled most efficiently; ECCs belong in hardware, other flash management functions belong in software. While managed NAND certainly has its place and its appeal in the market, we believe the best combination of value, performance and flexibility lies in using a combination of raw NAND and hardware with built-in ECC capabilities.

Webinar on “Toxic” data management

michele — Fri, 07 Nov 2008 21:23:19 +0000

Successful data management can mean the difference between a reliable, user-friendly product, and a frustrating nightmare of corrupted data and a failed device. Your approach to this key component of good device design will either fast-track your product for success or prove toxic to its implementation and derail market adoption.
The experts on fast, reliable data management are coming together for a one-time exploration of the signs of a “toxic” data management strategy, and to offer advice on how you can make sure this doesn’t happen to your project.
Please join us on November 13th at 7:30am and 12:00pm Pacific Standard Time, for an interactive, moderated discussion between Datalight and McObject. Topics will include combating slow device boot and poor access performance, and how to save money on unnecessary processor upgrades.

Hope you can make it!

Datalight Cuts Boot Time in Half for New LG Navigator

michele — Thu, 06 Nov 2008 21:36:05 +0000

The Challenge
Recently, LG Electronics, a well-known Korean-based manufacturer of consumer electronics, created a multimedia-enabled portable navigator for the North American market. The LN790 features a 4.3” LCD screen, Bluetooth hands-free functionality, and video-enabled playback. Ruggedness and fast access to data are important to consumers in this market, so the device was designed to boot directly from a NAND mass storage environment using Windows CE. Unfortunately, LG product engineers had a difficult time getting the device to boot fast enough using CE’s FAL/FMD flash drivers. At just over two minutes, the startup time did not match LG’s reputation for high-performance consumer devices.

The Datalight Solution
As LG engineers went searching for solutions to the boot speed problem, they discovered that Datalight FlashFX® Pro uses a more efficient approach to managing bad blocks than CE’s standard FMD/FAL drivers, which can speed boot time significantly. This difference is especially apparent when the device is using a large NAND disk, because boot time is somewhat proportional to the size of the flash.
Why is FlashFX Pro more efficient? Startup with FAL requires the driver to read more data as part of its mount sequence, a lengthy process particularly if the disk is large. In contrast, FlashFX Pro requires a much simpler check of the media to complete the initial mount.

The Customer Payoff
After implementation of FlashFX Pro, LG engineers were delighted to discover that the device’s boot time was cut by more than half. By using FlashFX Pro instead of the native Windows CE drivers, LG designers were able to achieve the performance their customers expect from a premium-quality personal navigator. There was also an additional benefit they hadn’t counted on – FlashFX Pro support for over 200 flash parts means that the LN790 will be future-proof from flash parts going on allocation, unexpected price fluctuations, and end-of-life issues.

Migrating from mDOC: Options, Challenges and Benefits

michele — Wed, 01 Oct 2008 19:42:07 +0000

SanDisk recently announced that it is end-of-lifing several flash parts in the mDOC family and OEMs who were using these parts in their devices are now looking at viable alternatives. In order to help these affected customers make informed decision, we have published a new whitepaper on options for migrating from Sandisk mDOC flash family.

The paper is available at http://www.datalight.com/mdocwhitepaper/

SD Card Association announces eSD

michele — Fri, 12 Sep 2008 19:49:55 +0000

Just got the PR from SD Card Association (SDA) announcing availability of eSD - embedded flash technology standard (full release below). We applaud the development of standards that will make it easier for OEMs to meet the growing data storage demands in their devices. As a member of the SD Card Association, Datalight has long been a proponent of increasing the reliability of data storage. While the eSD standard will help with integration and hardware reliability challenges, it will also shift the spotlight to the shortcomings of traditional file systems. Building a fully robust and incorruptible product requires reliability throughout the entire hardware platform and software stack.

Full Press release

SD CARD ASSOCIATION INTRODUCES EMBEDDED SD
FOR MOBILE PHONES, CONSUMER DEVICES

New Embedded SD standard offers field-proven SD functionality
and design ease to increase device storage options

SAN RAMON, Calif. – Sept. 11, 2008 – The SD Card Association (SDA) announced today it will enter the embedded storage market with the Embedded SD standard for storage devices in November. The Embedded SD specification extends the widely adopted, market-proven SD interface to embedded storage, doubling device storage potential and easing platform design in mobile handsets and consumer electronics devices.

As next-generation mobile handsets and CE devices demand high-capacity embedded storage and flash management solutions, Embedded SD simplifies system engineering by leveraging well-known SD standards. It allows all removable, embedded storage devices and input/output (I/O) peripherals to utilize the same common interface. Embedded SD separates flash management from the host and provides manufacturers and consumers with the flexibility of up to 32 GB scalable high-capacity on-board memory, plus 32 GB of removable memory with any SD High-Capacity memory card.

“The miniSD and microSD form factors are the leading interfaces for removable storage cards for mobile handsets, currently dominating the market, and are expected to constitute 90 percent of all card slots in mobile handsets in 2010, according to our analysis,” said Nam Hyung Kim, director and chief analyst for iSuppli Corp. “The new Embedded SD standard is built on that leading SD standard and takes aim at mobile handset storage needs like low power consumption, boot functionality, small form factor and integrated flash management.”

The Embedded SD standard regulates the specifications of SD interface-based embedded flash devices, easing the integration of storage devices and avoiding market fragmentation in the mobile and CE industries.

The Embedded SD specification defines the mechanical and electrical framework of the new embedded form factor and is also focused on enabling advanced functionality in embedded storage devices. Embedded SD devices offer a smart system solution with a smooth migration path from legacy designs, reduced design complexity and support for code, applications and user data storage.

“The SD Card Association plans to significantly reduce market fragmentation by delivering superior compatibility to the world of embedded storage, just as we have done in the storage card industry,” said James Taylor, president and chairman of the SD Card Association. “The association will continue to drive significant host market expansion while maintaining backwards compatibility with future interface development. The continuous collaboration and cooperation within the association’s ecosystem serves as a strong engine for innovation, consistency and growth.”

To speed adoption of Embedded SD, support of boot functionality requires only minor changes in the host ROM code of currently mass deployed baseband, application and multimedia processors with minimal additional changes to block device driver to support the additional functionality of embedded SD.

The Embedded SD Standard Defined:

•         Fully Compatible with SD standard – Embedded SD is fully compatible with the industry leading SDHC (SD 2.00) interface, ensuring a seamless migration from current SD to Embedded SD designs.
•         Both 3.3V and 1.8V Power Supplies – Supported for both flash and I/O power sources.
•         Boot from Embedded SD – Reliable and secure storage of boot code on an Embedded SD device reduces the number of memory components in a design, as well as the number of busses required, enabling more efficient designs.
•         Flexible Partition Mechanism – Allows multiple physical partitions accommodating varied data sources such as boot code, OS, applications and multimedia content with customizable levels of protection for each partition. Original equipment manufacturers, mobile network operators and content providers gain optimal flexibility and control to configure the Embedded SD device for different usages and data types.
•         Protection Mechanism – Flexibility to separately configure each physical partition with different read and write/erase protection modes.
•         Data Robustness – Optional configuration of each physical partition of the Embedded SD device, including full immunity to power failure and protection of critical data (boot code, operator data, etc.).
•         Power-Saving Sleep Mode – Option to customize power needs and reduce power consumption and boost battery life.

SD Card Association
The SD Card Association is an open industry standards organization established in January 2000 by Matsushita Electric (Panasonic), SanDisk and Toshiba, and is supported by a consortium of more than 1,100 companies. The SDA’s mission is to set industry standards and promote SD product acceptance in a variety of applications. SD Memory Card standards are currently being built into a wide range of digital products such as cellular phones, audio players, automotive multimedia systems, handheld PCs and digital video and still cameras. For more information about SDA, please visit the association’s web site, www.sdcard.org. Parties interested in joining SDA are encouraged to visit the web site or contact helpdesk@sdcard.org.

Reliance usage in a boot code update scenario

michele — Thu, 11 Sep 2008 19:30:25 +0000

There are two possible configurations in how boot code might be stored on a device

Boot code is stored in raw flash (no file system) and directly accessed from bootloader
Boot code is stored on a Reliance formatted flash volume

Option 1: Raw flash
If the boot image is being stored in RAW flash outside the file system, then the only way to be able to ensure that you got an update without damaging the original would be to reserve extra RAW space such that you could simultaneously have two boot images. The bootloader now needs to be able to switch between them and/or locate both of them The process of updating the boot image to a new location would include erasing the old image after updating the new, and having some sort of checksum to ensure the image was intact in case both were still there.

In this case, there would be no really good way to protect the update of the file to that exact same location without compromising the boot image itself. Many customers still use this way to store their boot images, but of course this means that they can’t take advantage of disabling transactions, atomically updating the boot image, and then doing a single transaction to commit all (or none) of the changes.

Option 2: Reliance
In this case, customer would not have a bootloader that checked a physical location for a boot image – they would have a bootloader that opened a file in the Reliance file system at boot time instead, if they were using a file system. Datalight Reliance comes with an utility called “Datalight Loader” which includes a lightweight Reliance reader. This utility integrates seamlessly in your bootloader code and allows the bootloader to mount and read Reliance partitions. Since the bootloader is capable of “reading” a Reliance disk, it doesn’t care where in the file system Reliance stores the file – it just opens the file, and loads it.

In this mode, while updating the boot image, the update utility disables all transactions and initiates the boot image update. Reliance never overwrites live data and hence this new boot code is written to a free-area of the flash. Once the entire boot image code is written, the bootloader calls for a manual transaction event, in which we update the metaroots to point to the new boot code area as the committed area. Old boot code area is now marked as free and can be used for future operations.

If power loss occurs during this replacement process, the device still boots back using the previous boot image, which was never modified

Perspective on the Flash Memory Summit 2008

michele — Tue, 02 Sep 2008 19:51:01 +0000

A week of SSD, NAND questions and New Technology

It’s hard to believe that it’s been 20 years since the invention of flash memory, but the 20-foot timeline documenting its milestones that was displayed at this year’s Flash Memory Summit offered ample evidence of the progress the technology has made. Attendance at this third Summit once again broke records set by previous shows and the energy of the attendees was high. At more than 1,300 registered attendees, 2008 was at least 25% larger than 2007. Having been a sponsor since the show’s inception, we can confirm that it was even more packed this year. Most of the keynote presentations spilled out of the main hall, and people were stacked up into the hallway trying to hear what was being said inside. The quality of the presentations once again proved worth the trip to Santa Clara, but it was obvious to everyone that the show is quickly outgrowing the Santa Clara Marriott.

The unofficial theme this year appeared to be solid-state drives (SSD), but beyond the SSD buzz, there were many presentations on designing NAND-based products, software optimization of flash, future technologies, and other flash-related topics of interest. Datalight gave four presentations (Flash Interfaces 101), and organized a forum on using flash in embedded as well as a full-day “executive update.”

There were a couple of keynote addresses we found particularly interesting and entertaining:

Dean Klein from Micron gave a speech entitled, “A Closer Look at NAND Flash.” Highlights of Dean’s keynote included a map of NANDs progress through the Gartner Cycle of Hype,

Gartner Cycle of Hype – Source: Gartner Research

in which he asserted that NAND is over the “peak of inflated expectations,” heading down into the “trough of disillusionment.” Klein jokingly referred to hard-drives several times as “rotating rust,” and the address featured an entertaining series of video clips along the lines of Apple’s Mac vs. PC ads, in which Hard Drive was escorted by Flash to a therapy session to talk about his sluggishness, forgetfulness, narcolepsy, and overeating (power consumption).

Eli Harari from SanDisk gave a keynote called “Changing the World: The Flash Memory Revolution.” Eli’s speech was less humorous than Dean’s, but no less interesting to listen to. He showed several timelines describing the evolution of flash applications, and a chart predicting that NAND demand will outstrip supply by 2011, allowing flash vendors to raise prices (!) and finally get a return on their investment in the technology. He also compared the progress of NAND density to Moore’s law, showing that NAND is tracking far ahead of where Moore’s law says it should be. He theorized that the next flash technology will be 3D NAND, and gave a fascinating demonstration of how it’s built and how it works, including photographs of 3D NAND’s unique architecture.

Spansion showed their ecoRAM: basically flash in a DIMM form factor. Cool. And eco-friendly, apparently. This new class of flash promises to reduce the power requirements for large server applications, using an eighth of the energy of DRAM, with better reliability, and read performance fast enough to meet the rapid access requirements of large-scale server installations.

Which highlights another key theme of the Summit: Power. How can flash help reduce global warming? Can SSDs make data centers run more economically? Uh, did I say “data centers?” Yes, surprise! While last year’s Summit saw the invasion of the laptop, this year a significant portion of the sessions addressed opportunities in the Enterprise segment.

But the “Big E” didn’t totally eclipse the “Little e” (embedded). There is still a growing need for low power, high performance flash soldered onto boards and into removable cards for embedded systems. The embedded track had presentations ranging from the basics of flash interfaces and differences between NOR and NAND to complex design methodology and frequency sources for flash memory applications.

Speaking of last year’s Summit, where Hybrid Hard Drives (traditional hard disk drive with flash caching) battled SSDs for attention, whatever happened to the HHDs? The only sign of them we saw was a presentation from Seagate wherein they said there is still work to do, particularly on the software (i.e., Windows Vista).

Our take overall? Industry insiders’ perspectives are essential for long term planning and this show is the place to get them. But all that crystal-ball-gazing can be a bit out of phase with where customers are today. SSDs are interesting and undoubtedly will be a key component in many future designs, but the reality is that migration from NOR-only systems to those that include both NAND and NOR or just NAND continues to be the mainstay for today’s designs. An analyst from IDC cashed a reality check on the SSD hype when he put up a slide showing relative market sizes of flash memory (big), hard disk drives (huge) and SSDs (tiny).

While many flash manufacturers are in an oversupply situation on NAND, others have parts on allocation. The industry as a whole is looking for ways to reduce costs and keep (or get) fabs profitable. This causes lower volume, lower margin product lines to be discontinued, sometimes just as designs using them are about to go to market.

Bottom line? The Flash Memory Summit provides a great opportunity to step outside our day-to-day reality and consider the possibilities promised by emerging technology. Next year’s Summit is sure to be a must-attend event for gaining planning perspective. We hope to see you there!

If you missed the Summit, presentations should be available soon at www.FlashMemorySummit.com. Bill’s presentation on flash interfaces, complete with narration, is available now: Flash Interfaces 101

Reliance Transactional File system demo

michele — Thu, 21 Aug 2008 20:15:47 +0000

Demonstrating how system software work in a visual manner is an interesting problem, especially in embedded space. There is no UI or visual effects to WOW the audience. To evaluate the value system software components bring to an embedded design, the customer usually needs to configure our software on his embedded development board. This provides for comprehensive evaluation but can be a significant effort. . We run into this very often at Datalight since our primary products (FlashFX Pro and Reliance) are system level embedded software. One way we have attempted to demonstrate our software is to make a full-functional version of our software run on user’s desktop PC. This allows the customer to run the software without any special hardware in matter of minutes and understand the core working of our software. Once they believe there is value, the can request source code access and try it on the actual embedded hardware.

The first demonstration that we have built is for Datalight Reliance. This demo is available to all users who are registered for MyDatalight account. The video below shows how you can use this software on any Windows PC and understand how Reliance unique transactional design allows for 100% reliability against data corruption and how Dynamic Transaction Point technology allows developers to tune their file system even while the device is running.

Datalight Flash File System Boosts Performance for Devices Built with MontaVista Linux

michele — Tue, 12 Aug 2008 04:35:16 +0000

Bothell, Wash., – August 12, 2008 – Datalight announced today that it has released new versions of Reliance™ and FlashFX® Pro, with pre-configured support for MontaVista® Linux®. The new install experience includes simplified integration within MontaVista DevRocket, an Eclipse-based IDE that streamlines common embedded development tasks. Dropped into DevRocket, Datalight products build as kernel loadable modules that work with a project’s OS image. Sample bootstrap code is also supplied for developers who need to integrate the products into a boot loader.

“Developers choose MontaVista Linux for faster time-to-market, integration, and stable, fully tested code. We are pleased that Datalight has extended these benefits at the flash memory file system level, and to provide embedded Linux developers with added performance and reliability,” said Dan Cauchy, Senior Director of Market Development, MontaVista Software.

Other upgrades include a read-only version of Reliance inside the Datalight Loader. This small footprint version permits a bootloader to load an OS image directly from a reliance partition. Devices benefit from risk-free “in-place OS upgrades” enabled by the application-controlled transaction point feature of Reliance. The new versions also feature enhancements in reliability, as well as support for a wide range of new flash parts. FlashFX Pro now supports Spansion NS-P, Samsung FlexOneNAND, Micron 55nm flash parts, and all CFI-compliant NOR parts. The Datalight flash file system solution is comprised of the Reliance file system and FlashFX Pro intelligent flash media manager. Reliance was designed from the ground up for high reliability applications. Dynamic Transaction Point™ technology provides 100% immunity from file corruption, even after unexpected system interruption. Embedded applications can benefit from faster boot times that remain consistent for the life of the product, regardless of disk size.

FlashFX Pro features pre-written support for over 200 flash parts, works with virtually any NAND controller, and features wear leveling, bad block management, and garbage compaction for unrivaled performance. Datalight flash file system products are also available on other operating systems and integrated development environments.

Datalight Flash File System Boosts Performance for Users of Wind River Linux

michele — Tue, 12 Aug 2008 04:30:18 +0000

Bothell, Wash., – August 12, 2008 – Datalight announced today that it has released new versions of Reliance™ and FlashFX® Pro with preconfigured support for Wind River Linux. The new install experience includes simplified integration with Wind River Workbench, an award-winning, Eclipse-based development platform. Dropped into Wind River Workbench, Datalight products build as kernel loadable modules that work with a project’s OS image. Sample bootstrap code is also supplied for users needing to integrate the products into a boot loader.

“Developers choose Wind River Linux for our broad range of hardware support and stable code base. Our VxWorks customers have enjoyed the benefits of the Datalight flash file system platform for years, and we are pleased that Wind River Linux customers now have the option of adding Datalight performance and reliability to their designs,” said Paul Anderson, vice president of Linux product engineering at Wind River.

Other upgrades include a read-only version of Reliance inside the Datalight Loader. This small footprint version permits a boot loader to load an OS image directly from a reliance partition. Devices benefit from risk-free “in-place OS upgrades” enabled by the application-controlled transaction point feature of Reliance.

The new versions also feature enhancements in reliability as well as support for a wide range of new flash parts. FlashFX Pro now supports Spansion NS-P, Samsung FlexOneNAND, Micron 55nm flash parts and all CFI-compliant NOR parts.

The Datalight flash file system solution is comprised of the Reliance file system and FlashFX Pro intelligent flash media manager. Reliance was designed from the ground up for high reliability applications. Dynamic Transaction Point technology provides 100 percent immunity from file corruption, even after unexpected system interruption. embedded applications can benefit from faster boot times that remain consistent for the life of the product regardless of disk size. FlashFX™ Pro features prewritten support for more than 200 flash parts, works with virtually any NAND controller and features wear leveling, bad block management and garbage compaction for unrivaled performance. Datalight flash file system products are also available on other operating systems including Wind River VxWorks.