Join us March 18th at 11am PDT as Datalight CEO Roy Sherrill and Wind River Product Manager Bill Graham weigh the pros and cons of switching to NAND. Maximize the usability and efficiency of your device memory by understanding all the considerations that go into integrating a NAND flash with your device’s software. Learn more and reserve your spot today as space is limited.
Palm just announced the 1.1 update to its popular WebOS that runs on the Palm Pre device. Apple released the 3.0 update to its Mac OSX for the iPhone and iPod touch. Microsoft is expected to launch Windows Mobile 6.5 soon and users are hoping that they will be able to update their 6.1 devices to 6.5. Google last month updated Android OS to 1.5. These events point to a recent and very fast growing phenomena: embedded devices are becoming more and more like PCs where users expect to be able to update their device long after it has been released. This was not always the case; OEMs refrained from updating embedded devices unless in cases of high severity bug fixes. There are several reasons for this:
Today’s blog post focuses on #3 because it has very real technical risks and solutions. Before we begin discussing risks of bricking device, let’s talk about 2 different types of updates
If the update is of type 1, then the process has less likelihood of bricking the device. In most cases even if the update fails, support can help user start the device in “safe” mode and restore. Updates of type 2 are by nature riskier because any failure is likely to stop the device from booting up, negating any remote debugging options. Note that It is also possible that for some devices, the application and system code is stored in single boot image. In that case, the distinction of types made above are irrelevant for this discussion.
OS/System Updates
Here is how devices typically partition the data storage for boot and application data
Note: Some devices may not use the file system for the boot partition and instead directly talk to the block device. In that case, the remainder of this discussion is not applicable.
During an update process involving system code, the boot image has to be replaced with a new one. Typically the update process will overwrite the existing image. The problem happens when the update process is interrupted due to erroneous circumstances such as
In these cases, the OS image will get corrupted and the device may not be able to boot back up, leading to a bricked device.
One of the features of Reliance (and Reliance Nitro) file system is that it never overwrites live data. It will always use free space on disk or in case there is no space, it will give “disk full” error back to the application. Reliance also has a special transaction mode called “Application-controlled”. In this case, Reliance only conducts a transaction point when asked by the application. Here is how these 2 constructs help Reliance provide a fail-safe means of in-place updates
Using Reliance for boot partition can thus help in providing a safe in-place update process. It also has the advantage of using Reliance extreme fast mount times, which can help in speeding device boot speeds.
Note that the obvious caveat of the above is that there has to enough free space for the new OS image. With disk storage being cheap (compared to device cost) and always increasing, this becomes less and less of an issue. OEMs should strongly consider going this alternative (whether they use Reliance or not) in order to ensure that the device update process will go smoothly for the end users.
Sea Change Hits Consumer Electronics as Customers Demand Long-term Value
For the first time in more than a decade, people are saving again. In 2007 and years prior, the savings rate hovered around zero as we maxed our credit cards and lines of credit, driving the savings rate into the red and giving the world’s manufacturing base an almost unbelievable boom. In January 2009 though, something unexpected happened; the US savings rate suddenly moved above 5%, the highest in decades. As news of our cloudy economic picture has emerged, consumer behavior is shifting away from status-seeking luxury purchases toward more value-based buying patterns, forcing manufacturers around the world to take notice. And after decades of excess, the shift to thrift is looking like a lasting trend.
But what does this mean for Embedded? As consumers focus on needs over wants, they will increasingly seek out products that are proven durable and reliable.
This will have broad implications for manufacturers of everything from cars to clothing, refrigerators to embedded devices. Today’s consumers are choosing efficiency, durability and value over gee-whiz gadgetry. Consumer mobile OEMs too must focus on delivering value and fewer, more targeted features. Rather than packing devices full of a laundry list of apps and expensive hardware, this means streamlined offerings and more segmented products, while making sure the consumer doesn’t feel like they’re missing out. Motorola’s new EM330 is a prime example of this kind of pared-down, demographic-specific approach. The phone, called the MOTOROKR STAR is marketed specifically toward music lovers, offering a basic clamshell with music recognition software and download-on-the-go at a price point in the sub-$200 range.
As OEMs scramble to add value and enhance their reputations for durability and reliability, Datalight responds with products that support those goals. The combination of flexible flash management that lowers bill of material costs, wear-leveling algorithms extend flash life by several times, and the rock-solid reliability of our file system become essential components of a strategy to provide value to customers.
Many have remarked that markets are driven by a combination of fear and greed. Though the pendulum has recently taken a dramatic –and we believe temporary– move in the direction of fear, ultimately we know a move away from excess is good for all of us and good for the world we live in. Here’s hoping the trend toward value and quality is a long-lasting one.
OEMs Position Themselves for the Economic Turnaround
As everyone’s mother used to say, “When life hands you lemons…” And at this particular time in embedded technology and elsewhere, it seems there is no shortage of them. In just the last three weeks, we’ve heard about Nortel filing for bankruptcy, Motorola planning to cut 7,000 jobs, and Sony Ericsson’s dramatic profitability swing from $1.48 billion in 2007 to negative $96 million in 2008. And yet, one thing we know about recessions is that they inevitably end in expansion. The only question is when. With the fresh winds of optimism blowing in from Washington this week, now is as good a time as any to start planning your strategy for survival followed by world domination.
Indeed, if there is a silver lining to our current situation, it has to be the unprecedented opportunities for well-positioned, forward thinking companies to dominate their markets. Clearly, this takes grit, an eye on keeping costs down, and a truly differentiated product strategy. It’s more important now than ever before for OEMs to focus on their core competencies, keep bill of materials costs low and work with vendors who have experience weathering economic storms and possess the fortitude to survive tough times.
Datalight was born in 1983 during one of the worst recessions in the post-war era, and we remember well the challenges of the early 90’s and the aftermath of 9/11/01. While many of our competitors are pulling resources from flash file system development, we are moving ahead with a full schedule of product releases and innovation for 2009. While at CES this year, we discovered one of our competitors is pulling out of the flash file system business altogether. I won’t bore you with a long-winded sales pitch, because chances are if you’re reading this newsletter you already know Datalight can help you build better products with lower development costs and give you the ability to choose between the least expensive of over 300 NAND and NOR flash parts.
Like our new president, we are cautiously optimistic about the coming year. As President Obama said so well, this economy is going to take hard work and a little time to turn around. One thing we know for sure though, is that the turnaround is coming. Companies that design products their customers need and want, continue to invest in technology and communication, and prepare themselves to capitalize on a business environment with fewer competitors will do extremely well in the coming years.
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.
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.
Consumer electronics and embedded software devices are using larger amounts of flash memory for nonvolatile storage than ever before. So what kind of flash memory should you use? The choice between using NAND and NOR Flash may not be a simple one for the complex embedded devices being developed today. While ever-larger media files are driving increased demand for inexpensive NAND, powerful new operating systems and intricate applications running on fast processors ask for the fast-executing code NOR can support.
Read Datalight whitepaper Choosing NAND or NOR Flash Memory: Tradeoffs and Strategies to Learn More
Consumer electronics and embedded software devices are using larger amounts of flash memory for nonvolatile storage than ever before. One important decision in designing such devices is what kind of flash memory to use: NAND or NOR?
NOR flash memory has traditionally been used to store relatively small amounts of executable code for embedded computing devices such as PDAs and cell phones. NOR is well suited to use for code storage because of its reliability, fast read operations, and random access capabilities. Because code can be directly executed in place, NOR is ideal for storing firmware, boot code, operating systems, and other data that changes infrequently.
NAND flash memory has become the preferred format for storing larger quantities of data on devices such as USB Flash drives, digital cameras and MP3 players. Higher density, lower cost, and faster write and erase times, and a longer re-write life expectancy make NAND especially well suited for consumer media applications in which large files of sequential data need to be loaded into memory quickly and replaced with new files repeatedly.
The choice between using NAND and NOR Flash may not be a simple one for the complex embedded devices being developed today. While ever-larger media files are driving increased demand for inexpensive NAND, powerful new operating systems and intricate applications running on fast processors call for the kind of fast-executing code NOR can support. An important example is a smart phone or PDA that combines a tremendous need for storage with a demanding set of application performance requirements. In some cases an optimal design might call for both types of flash memory in the same device.
Whichever type of flash is used in a device, there are certain negative performance characteristics that need to be mitigated. NOR is fast to read current data but markedly slower to erase it and write new data. NAND is fast to erase and write, but slow to read non-sequential data through its serial interface. NAND is also prone to single-bit errors, requiring rigorous algorithms for error detection and correction.
Well-designed software strategies can be very effective in increasing the performance and reliability of Flash hardware. The goals of flash memory management software include:
Avoid loss of data. Perhaps the most important goal in managing flash memory is to assure that no data is ever lost as a result of an interrupted operation or the failure of a memory block. There are several ways that flash management software can achieve this goal. Rewrite operations, for example, can be managed in such a way that new data is written and verified before the old data is deleted, so that no power loss or other interruption can result in the loss of both old and new data. Bad block management is another important safeguard to prevent data being written to memory blocks that have failed. Software can check for bad blocks shipped from the factory, as is typical with NAND, and avoid writing to those blocks from the beginning. When blocks go bad over time they can be identified and managed so that they are no longer used. Finally, as the end of media life nears, good memory management software can implement a graceful strategy such as placing the entire flash unit in a read-only state, thereby avoiding data loss when the number of block errors exceeds a predefined number.
Improve effective performance. Two ways media management software can improve performance are background compaction and multithreading. Compaction reclaims space by identifying blocks that have obsolete data that can be erased, copying any valid data to a new location, then erasing the blocks to make them available for reuse. Such compaction increases the amount of usable space on the media and improves write performance. Compaction may also help to defragment noncontiguous data for improved performance on read operations. The space recovery is particularly valuable for the more costly NOR memory and the defragmentation benefits the slower-reading NAND. Compaction is best performed in the background during idle time, however, or it can interfere with critical operations and degrade performance. This is where a multithreading system becomes important. By allowing high-priority read requests to interrupt low-priority maintenance operations, a multithreading system can reduce read latency by orders of magnitude compared to a single-thread solution.
Maximize media lifespan. When some blocks of memory contain fixed content, such as binary code, the remaining blocks will experience increased demand for erase and write operations, leading to earlier failure. Wear-leveling algorithms can prevent overuse of memory blocks and prevent a “stalemate” scenario in which a small region of memory becomes locked in a pattern of repeated writing and compaction. Wear leveling software can monitor block usage to identify high-use areas and low-use areas containing static data, then swap the static data into the high use areas. It can also balance write operations across all available blocks by choosing the optimal location for each write operation.
The decision between NAND and NOR memory will ultimately depend on both technical and pricing requirements of the device being built. Whatever type or combination of flash is used, it is prudent to include memory management software to prevent data loss while improving the performance and maximizing the lifespan of the memory.
Interesting piece of news today – Digitimes is reporting that Samsung has informed its customers that it will be reducing supply of NAND Flash chips because of the huge order placed by Apple. This story is being picked up by several news outlet including Engadget. While this is good news for Apple and all those vying for the 3G iPhone, it underscores the challenges other OEMs that depended on Samsung Flash will be facing. NAND flash market is very volatile with demand – supply economics changing rapidly. Intricacies of flash memory force most OEMs to rely on a single vendor for supply, that way they do not have to implement support for several flash parts in their design. While this may seem the easier route, situations such as today’s causes production to come to halt or a significant redesign, both which are very expensive alternatives.
One of the ways to reduce such risk is to include support for multiple flash parts and use multi-sourcing to source flash parts from 3-4 flash vendors. If you are using an intelligent flash manager like FlashFX Pro , you are already covered since FlashFX pro supports 200+ flash parts from all top flash vendors. For others, it can still be done with some serious effort during planning and design time. Consider this work as an insurance against an event such as today’s.
