By Steve Leibson for Denali Software

If you’re waiting for solid-state drives (SSDs) to overtake hard-disk drives (HDDs) as the storage device of choice in computers, servers, and consumer devices then Objective Analysis’ Jim Handy has a message for you: It’s not happening any time soon. Handy’s been following storage trends for many years. He’s tracked the pricing trends of HDDs for a while and SSDs for their short but dynamic life. Based on his presentation at the recent Storage Visions 2010 conference in Las Vegas, here’s what Handy forecasts:

Courtesy of Objective Analysis (www.objective-analysis.com)

The cost/Gbyte for HDDs is roughly 20x lower than for SSDs and Handy expects that relationship to be stable for the next 20 years. Sure, the cost/Gbyte will decrease for both types of storage device, but HDDs will remain the low-cost leader for high-capacity storage.

These predictions are built on some “basic truths”:

• HDD capacity doubles every year or two
• The minimum price for an HDD seems to have bottomed out at $50
• NAND Flash device capacity also doubles every year or two
• When NAND Flash stops scaling (see the previous Denali Memory Report blog post “The End of NAND Flash as we Know It: Micron’s Dean Klein and Samsung’s Tony Kim Look at Life After Flash”), some other non-volatile semiconductor memory will come along to continue the cost/Gbyte trend for SSDs

These raw numbers are fascinating, but the implications for storage consumers and marketers are even more interesting. For example, Handy asked the question “What can you do with $10 of NAND Flash memory now and what will you be able to do with it in twenty years?” He answered that question with the following graph:

Courtesy of Objective Analysis (www.objective-analysis.com)

Today, you can store about a thousand songs on $10 worth of NAND Flash memory. You can store perhaps one or two standard-definition (DVD-quality) movies or two HD (Blu-ray quality) movies. As NAND Flash capacities rise, you’ll be able to store more music and more movies for that same $10. Around the year 2026 or 2027, said Handy, you’ll be able to store the entire iTunes music catalog—all 10 million songs—on $10 worth of NAND Flash. That information nugget suggests that there will someday be consumer-class devices that will ship pre-loaded with every song you might ever want and that you’ll merely pay a fee to unlock the songs that you want to hear. Don’t believe it? Well, back in the year 2000, the music companies didn’t believe they’d be selling songs by subscription instead of quaint plastic discs called CDs. Now CD sales are way down and iTunes rules the roost with downloadable music.

Then Handy asked a similar question about HDDs: What can you do with a $50 HDD? Here’s the graph he showed to answer that question:

Courtesy of Objective Analysis (www.objective-analysis.com)

Today, you can store more than 100,000 songs or 100 DVD-quality movies on a $50 HDD. By the year 2017, you’ll be putting the entire iTunes catalog, all 10 million songs, on that same HDD. By the year 2025, you’ll be able to fit the entire Internet Movie Database (www.IMDB.com) movie catalog—500,000 films—on one $50 HDD. By then, once again, you may be buying a consumer product preloaded with every movie ever made and simply paying a fee to watch the movies you want.

Handy claims that people will eventually collect movies on hard disk as they do now for music. Currently, people buy or rent DVDs and Blu-ray discs rather than keep them in HDD storage but eventually media storage will be so inexpensive that even movies will disappear comfortably into the maw of a $50 HDD. A subsequent panel of teenager media users underscored that point at Storage Visions 2010. The young panelists described their current media-consumption habits. Unlike their parents, they never buy music CDs unless giving them as gifts. They download all of their music. However, they currently do want physical DVDs and Blu-ray discs. Their children probably won’t.

By Steve Leibson for Denali Software

Today, NAND Flash is king of the semiconductor memories in terms of cost per bit, a position it has held since 2004 or 2005. Consequently, NAND Flash serves as the technology driver for semiconductor processing—a position previously held by DRAM, processors, and FPGAs. The top NAND Flash semiconductor vendors are currently fabricating NAND Flash memories using 3x nm lithography (34nm for Intel and Micron, 30 nm for Samsung). By some technology estimates, there are now only two generations left in the life of NAND Flash as we know it today. At the current pace of NAND Flash generational development, two generations equals 36 months. After that, NAND Flash device capacity will clearly stall unless some new development changes the fundamental design of the NAND Flash semiconductor memory cell. That's not just alarmist talk for the purpose of controversy. One of the people making such claims is Micron's Dean Klein, Vice President of Memory System Development, who delivered these warnings in a keynote at Storage Visions 2010 held earlier this month in Las Vegas, just before CES.

The Incredible Shrinking NAND Flash Memory Cell
(From the keynote presentation by Micron’s Dean Klein)

Some of the looming NAND Flash problems involve the inability of smaller-geometry Flash memory cells to safely handle the high programming voltage (25V) needed to induce electron tunneling, memory-cell crosstalk, parametric degradation of dielectrics at shrinking geometries (layers are now just a few atoms thick), and the fact that NAND Flash cells are already so small that the presence or absence of fewer than 200 electrons on the floating gate makes the difference between a digital zero and a one. Because of these growing problems, said Klein in his keynote, it will be very difficult to employ semiconductor process geometries smaller than 20nm for existing NAND Flash memory cell design. Klein then took one step back from the brink by noting that people previously said NAND Flash could not break through the 40nm barrier but obviously it did.

Semiconductor process and design wizards found ways to overcome those limits and those same wizards are searching for ways to overcome the present problems, but there is not yet enough visible progress to believe that a solution is imminent said Klein. One possible path to a solution is to employ 3D or vertical NAND Flash cell stacking, which would double chip capacity without shrinking the memory cell size. If successful, 3D stacking could add another two NAND Flash generations and postpone the need for a NAND Flash replacement technology for five to eight years according to Klein. NAND Flash vendors will use 3D stacking if it proves sufficiently practical, but only if it's practical.

In the end, semiconductor vendors always take the path of least resistance, said Klein, and there are candidate technologies that promise non-volatile alternatives to NAND Flash. Klein listed MRAM (magnetic RAM), FRAM (ferroelectric RAM), PCM (phase-change memory), resistive RAM, and crosspoint memory as candidate replacement memory technologies. Again taking a step back, Klein then stated that all of these replacement memory technology candidates currently have warts but his personal pick for the eventual winner is PCM.

Micron isn't the only semiconductor vendor staring down the loaded barrel of the NAND Flash scaling problem. In a one-on-one interview just prior to Klein's keynote, Samsung's Flash Marketing Director Tony Kim said much the same thing. Going to smaller NAND Flash geometries is becoming very difficult said Kim. Vendors are investigating different materials and designs for the NAND Flash memory cell’s floating gate, different cell architectures, 3D stacking, and multi-level cells (storing more than one bit per physical memory cell). However semiconductor technologists can see that time is growing short, there is an end to the technology, and so they're all seeking a high-volume semiconductor technology that will overthrow the current king of non-volatile memory, NAND Flash.

By Steve Leibson for Denali Software

If you spend a lot of time reading and thinking about solid-state drives (SSDs), you may have gotten the impression that NAND Flash storage is at odds with hard-disk storage—that it's a winner-take-all situation. In his keynote at last week's pre-CES Storage Visions 2010 conference in Las Vegas, storage analyst Tom Coughlin dispelled that notion with some cogent slides and some insightful analysis. Coughlin founded the Storage Visions conference; he's the chairman of the annual Flash Memory Summit; and is the author of Digital Storage in Consumer Electronics published by Newnes Press in 2008. According to Coughlin’s free companion White Paper Flash & HDD – Symbiosis, or Survival of the Fittest (published under his Objective Analysis market-research banner), Flash-based consumer applications such as personal music and video players, digital still cameras, and camcorders actually contribute to additional sales for hard disk drives (HDDs).

Coughlin began his keynote remarks with the following forecast slide, which shows the shipped storage capacity for optical disk drives (ODDs), HDDs, and NAND Flash devices from 2006 through 2014. HDDs will still be carrying the bulk of the capacity load by the year 2014 but NAND Flash’s storage share will grow significantly, to 274 exabytes of storage shipped compared to 427 exabytes of storage for HDDs. (One exabyte equals one billion Gbytes.) Note that Coughlin's prediction suggests that 2014 will be the first year that NAND Flash annual shipped capacity will exceed the annual shipped capacity of optical drives.

How do these immense numbers arise and where's the symbiosis between HDDs and NAND Flash memory? In his White Paper, Coughlin lists three examples of consumer applications where NAND Flash sales depend on and support HDD sales: digital still cameras (DSCs), personal music and video players (PMPs), and Flash-based camcorders.

According to Coughlin's White Paper, the average DSC user shoots an average of 549 photos per year and the average photo size is 4.7 Mbytes. That's roughly 2.6 Gbytes of photos per DSC user per year that needs storage. DSC and camera phone sales are rising at 5% per year, the average image size as measured in Mpixels is growing at 25% per year, and the number of photos that DSC and camera phone users are generating appears to be rising at a rate of 24% per year. Do the math and you'll find that the amount of storage needed to hold these photographs is increasing at a compound rate of 63% per year, based on Coughlin’s assumptions. As a result, almost two million drives per year will be sold to store digital images in 2014.

Couglin notes a similar symbiosis for HDDs with respect to PMPs. He writes that the average PMP owner's music and video storage needs are roughly 3:1 for HDD and PMP storage space. With the average PMP storage capacity now at 4 Gbytes, that's presently 12 Gbytes of HDD storage for each Flash-based playback device. In addition, most downloaded music and video must pass through a PC’s HDD (internal or external) before ending up on the PMP, which makes the HDD's existence that much more critical to PMP use. Again using some simple growth assumptions, Coughlin expects that PMPs will drive incremental HDD sales of 42 million just for music and video storage by 2014.

Using similar scenarios, Coughlin predicts that Flash-based camcorders will drive sales of an additional three million HDD sales in 2014 and online (cloud-based) storage for consumer images, video, and music will drive sales of an another incremental two million HDDs in 2014. The total comes to nearly 50 million incremental HDD sales annually—about 5% of total HDD sales—by the year 2014 as shown in the following figure. That’s symbiosis.

And what does NAND Flash get from this relationship? Coughlin posits that the availability of inexpensive HDD storage encourages the sale of DSCs, PMPs, Flash-based camcorders, and other Flash-based multimedia consumer products. In the case of camcorders, he goes even further, claiming that a majority of the projected Flash-based camcorder sales “would never be sold if hard drives weren’t available.” That’s symbiosis.

“Altogether,” writes Coughlin in his White Paper, “our projected 2.2 exabytes of Flash memory [sales] in 2014 (estimated to be 59% of the total consumer Flash demand) would be significantly smaller if HDDs were not available to support them.” That truly is symbiosis.

So if you were thinking that Flash in the form of SSDs and other Flash-based storage arrays were going to kill off HDDs in the near future, Coughlin would strongly disagree. He sees a long, cooperative future ahead for the two technologies and he has published data publicly to back up that claim.

by Marc Greenberg, Director of Technical Marketing, Denali Software

Momentum for LPDDR2 is building. It's mostly in the mobile space, and it's been in the general area of Handsets, MIDs, and other mobile devices. Both high-end and low-end handset customers are seeking LPDDR2 support, which is interesting since LPDDR2 was initially thought to be a high-end technology. Long-term, LPDDR2 devices are expected in a lot of embedded applications where DDR3 is unsuitable for various reasons.

When it comes to building chips today, the LPDDR2 market is still maturing and device availability is just now coming on-line, so chip guys need to hedge their bets by supporting at least one other memory technology, sometimes more.

The first hedge for pure handset folks is an LPDDR2/LPDDR1 combo. This allows them to get into a low-power memory with LPDDR1 or LPDDR2 technology, but the performance for this combo is limited by LPDDR1 which has a maximum clock rate of 200MHz (DDR400) and in reality, 166MHz is the popular frequency for LPDDR1. So, this doesn't work for high-end solutions since they are sacrificing performance or would need to deploy a wider interface.

The second hedge is DDR2. DDR2 makes a nice combo with LPDDR1/LPDDR2 because the IO voltage of DDR2 is 1.8v, same as LPDDR1, so you don't need a different oxide in the IO if you were already supporting 1.8v for LPDDR1. DDR2 is the low-cost memory leader and available up to 533MHz (DDR1066) today. So the LPDDR1/LPDDR2/DDR2 combo has been popular for most of 2009.

Lately, more companies are looking forward at DDR3. DDR3 offers the advantage of a 1.5v I/O and for the most part DDR3 is built on smaller process geometries so uses less power in general. The chart below shows a comparison of different memory technologies at the same throughput. The take-away from this chart is that a 16-bit DDR3 running at 333MHz (DDR667) is about the same power as a 32-bit LPDDR1 running 166MHz(DDR333) so there is equal throughput and similar power usage between DDR3 and LPDDR1.

This is not a completely fair comparison -- there are lots of things not considered:

• SSTL IOs of DDR3 use a lot more power than the LVCMOS pads of LPDDR1;
• DDR3 needs termination which uses power;
• Those 16 extra DQ pins (plus 2 DQ and 2DMs) required for LPDDR1 also use power;
• LPDDR1 can go into a low power mode more often and more easily;
• LPDDR1 uses less power in standby;
• etc…

So, let's look at the decision-making process: if I am a high end mobile customer, I need LPDDR2, that much is certain. I probably want to hedge my bets with another memory technology to ensure that I have supply of some memory in case LPDDR2 is expensive or unavailable. If I choose LPDDR1, I need to put down 2X the IO pins for data to get into a part that uses 10% less power than DDR3, remembering that LPDDR1 was first introduced over 6 years ago. Or, I keep the same number of IO pins, use the most mainstream memory for 2010 and beyond (DDR3), and live with 10% more power usage in my memory.

Finally, with mask costs and chip development costs being what they are, everyone has an eye on being able to use their chip in more than one application space. Even if the chipset is primarily mobile, with the projected cost of DDR3 being less cost per bit than DDR2 starting in 2010, DDR3 becomes a "must-have" for new chip designs.