Taking an Accurate Look at SSD Write Endurance
Last year, I posted a rebuttal to a paper describing the future of flash memory as ‘bleak’. The paper went through great (and convoluted) lengths to paint a tragic picture of flash memory endurance moving forward. Yesterday a newer paper hit Slashdot – this one doing just the opposite, and going as far as to assume production flash memory handling up to 1 Million erase cycles. You’d think that since I’m constantly pushing flash memory as a viable, reliable, and super-fast successor to Hard Disks (aka 'Spinning Rust'), that I’d just sit back on this one and let it fly. After all, it helps make my argument! Well, I can’t, because if there are errors published on a topic so important to me, it’s in the interest of journalistic integrity that I must now post an equal and opposite rebuttal to this one – even if it works against my case.
First I’m going to invite you to read through the paper in question. After doing so, I’m now going to pick it apart. Unfortunately I’m crunched for time today, so I’m going to reduce my dissertation into the form of some simple bulleted points:
- Max data write speed did not take into account 8/10 encoding, meaning 6Gb/sec = 600MB/sec, not 750MB/sec.
- The flash *page* size (8KB) and block sizes (2MB) chosen more closely resemble that of MLC parts (not SLC – see below for why this is important).
- The paper makes no reference to Write Amplification.
Perhaps the most glaring and significant is that all of the formulas, while correct, fail to consider the most important factor when dealing with flash memory writes – Write Amplification.
Before geting into it, I'll reference the excellent graphic that Anand put in his SSD Relapse piece:
SSD controllers combine smaller writes into larger ones in an attempt to speed up the effective write speed. This falls flat once all flash blocks have been written to at least once. From that point forward, the SSD must play musical chairs with the data on each and every small write. In a bad case, a single 4KB write turns into a 2MB write. For that example, Write Amplification would be a factor of 500, meaning the flash memory is cycled at 500x the rate calculated in the paper. Sure that’s an extreme example, but the point is that without referencing amplification at all, it is assumed to be a factor of 1, which would only be the case if you were only writing 2MB blocks of data to the SSD. This is almost never the case, regardless of Operating System.
After posters on Slashdot called out the author on his assumptions of rated P/E cycles, he went back and added two links to justify his figures. The problem is that the first links to a 2005 data sheet for 90nm SLC flash. Samsung’s 90nm flash was 1Gb per die (128MB). The packages were available with up to 4 dies each, and scaling up to a typical 16-chip SSD, that only gives you an 8GB SSD. Not very practical. That’s not to say 100k is an inaccurate figure for SLC endurance. It’s just a really bad reference to use is all. Here's a better one from the Flash Memory Summit a couple of years back:
The second link was a 2008 PR blast from Micron, based on their proposed pushing of the 34nm process to its limits. “One Million Write Cycles” was nothing more than a tag line for an achievement accomplished in a lab under ideal conditions. That figure was never reached in anything you could actually buy in a SATA SSD. A better reference would be from that same presentation at the Summit:
This shows larger process nodes hitting even beyond 1 million cycles (given sufficient additional error bits used for error correction), but remember it has to be something that is available and in a usable capacity to be practical for real world use, and that’s just not the case for the flash in the above chart.
At the end of the day, manufacturers must balance cost, capacity, and longevity. This forces a push towards smaller processes (for more capacity per cost), with the limit being how much endurance they are willing to give up in the process. In the end they choose based on what the customer needs. Enterprise use leans towards SLC or eMLC, as they are willing to spend more for the gain in endurance. Typical PC users get standard MLC and now even TLC, which are *good enough* for that application. It's worth noting that most SSD failures are not due to burning out all of the available flash P/E cycles. The vast majority are due to infant mortality failures of the controller or even due to buggy firmware. I've never written enough to any single consumer SSD (in normal operation) to wear out all of the flash. The closest I've come to a flash-related failure was when I had an ioDrive fail during testing by excessive heat causing a solder pad to lift on one of the flash chips.
All of this said, I’d love to see a revisit to the author’s well-structured paper – only based on the corrected assumptions I’ve outlined above. *That* is the type of paper I would reference when attempting to make *accurate* arguments for SSD endurance.
Subject: Editorial, General Tech | February 16, 2013 - 02:08 AM | Scott Michaud
Tagged: consoles, consolitis, pc gaming
If you really enjoy an Xbox or Playstation game, better hope your console does not die: it is likely that nothing else will play it. This news comes from a statement made by Blake Jorgensen, CFO of Electronic Arts. Clearly EA is a trusted partner of all console developers and not just an anonymous tipster.
You mean, Devil May Stop Crying?
I tend to rant about this point quite often. For a market so devoted to the opinion that video games are art, the market certainly does not care about its preservation as art. There is always room for consumable and even disposable entertainment, but the difference with art is that it cannot be substituted with another piece of content.
There would be a difference if someone magically replaced every copy of Schindler’s List, including the vaulted masters, with The Boy in the Striped Pajamas. I could safely assume that the vast majority of the audience for either film was not just browsing the Holocaust movie genre. I would expect the viewer was seeking out the one or the other for a specific reason.
This is incompatible with the console ecosystem by its design. The point of the platform is to be disposable and its content is along for the ride while it lasts. They often deliver the console for less than their parts and labor fees: research, development, and marketing costs regardless. The business model is to eliminate as many big fees as possible and then jack up the price of everything else ten bucks here and there. Over time you will not be given a bargain, over time you will give them more than they made you think you saved. They then spend this extra money keeping content exclusively under their control, not yours. Also, profits... give or take.
Again, there is always room for consumable entertainment. The consoles are designed to be very convenient, but not cheap and not suitable for timeless art. Really, the only unfortunate element is how these impairments are viewed as assets and all the while examples such as this one dance around the background largely shrugged off without being pieced together.
As for your favorite game? Who knows, maybe you will get lucky and it will be remade on some other platform for you to purchase again. You might be lucky, it might even be available on the PC.
Subject: Editorial, General Tech | February 16, 2013 - 01:19 AM | Scott Michaud
There have been some groups opposed to the planned deal to cease publicly trading Dell and release their shares. It would seem that for many, a short-term payout of 25 percent over trading price is insufficient and, they believe, undervalues the company. I mean, the price is totally not derived from the value you gave it when you just finished trading stocks at 80 percent of what Dell is offering you or anything. Yes, I am making a joke: some investors were almost definitely going long on Dell. I still suspect that some are just playing hardball, hoping that a quarter on the dollar raise is just a starting bid.
Buckle in, I will separate stockholders opinions into two categories: investment firms and employees.
Ars Technica clearly had football on the mind when they wrote a very Superbowl-themed editorial. Early in the month, Southeastern Asset Management sent a letter to Dell management expressing their stance to vote against a deal to go private. The investment firm controls 8.5 percent of Dell which means their opinion has a fair amount of sway. A short few days later, T. Rowe Price stepped up to likewise oppose the deal. This firm owns 4.4 percent of Dell, which means combined they have roughly a 13 percent vote.
Factor in a bunch of smaller investors and you are looking at almost a fifth of the company wanting to keep it public. That combined voting power slightly overtakes the 16 percent control owned by Micheal Dell and could hamper the festivities.
Employees, meanwhile, are upset all the same. Again, according to Ars Technica and their vigilant coverage states that some employees were force to sell their stock acquired as a part of their 401k at $9 per share – substantially lower than the 13.65$ being offered to investors.
There are several other ways which employees get their stake in the company reduced or hampered, but I would direct you to the Ars Technica article so I do not butcher any details.
Unfortunately these sorts of practices are fairly commonplace when it comes to investment deals. It would appear as if this deal trots on common ground instead of taking the high road.
God, I hate mixed metaphors.
Subject: Editorial, General Tech | February 9, 2013 - 02:49 AM | Scott Michaud
Tagged: windows blue
Could the sadness Microsoft feels with their OEM partners make the whole company feel just a little Blue?
I have been thinking about this while reading the latest news from Mary Jo Foley over at ZDNet. This has not been the first time that we have mentioned the color. Blue was, and still is, a codename for the first major feature-update of Windows 8. What we learned is that now it seems that “Blue” covers much more.
As many know, Microsoft has shifted their branding into four color-coded divisions: blue is for Windows; red is for Office; green is for Xbox, and yellow has yet to be disclosed. As far as we know, the Windows division encompasses Windows Phone, Internet Explorer, official apps, and so forth. Apparently “Blue”, the codenamed update, will start Microsoft on an annual update schedule for the Windows division. This means that Internet Explorer as well as the Mail, Calendar, Bing app, and other “Windows Services” such as SkyDrive and Hotmail will shift towards the yearly timer.
As I read Mary Jo's article, I focused on a point buried late in the second act of the column:
Instead of RTMing a new version of Windows once every three or so years, and then hoping/praying OEMs can get the final bits tested and preloaded on new hardware a few months later, Microsoft is going to try to push Blue out to users far more quickly, possibly via the Windows Store, my contact said.
While I have speculated about Microsoft and their desires to shift business models to a subscription service for quite some time, I have not considered OEM partners as a prominent reason. Microsoft has been wrestling with their manufacturers, that has recently been made obvious. The release of a new operating system drives users to go out and purchase new hardware. The PC industry bounces forward with software and hardware enhancements chained in lockstep to the three year Windows cycle, even the enthusiast market to some extent.
Perhaps Microsoft is trying to let the hardware itself drive the market. Instead of pushing the industry forward in big leaps, would it be possible that Microsoft wants the hardware to evolve and a new version of Windows to be there waiting for it?
Subject: Editorial, General Tech | February 5, 2013 - 05:44 PM | Scott Michaud
Tagged: Psychonauts, Notch, Tim Schafer
You cannot knock Tim Schafer: he abides by “Shut up and take my money”.
Last year we reported on the public negotiations between the heads of Mojang and Double Fine for a potential sequel to Psychonauts. The game was supposed to take “a couple” of million to make, which was later clarified to at least $13 million USD. This prompted the famous response from Notch, “Yeah, I can do that.”
Some time later, the deal fell by the wayside.
A storm never came that day, barely a ripple brushed against his wooden canoe.
Recently Notch was on Reddit and commented about the status of the sequel. The final budget ended up being around $18 million USD which ended up being beyond what Notch felt comfortable investing in. It was not for a lack of funds, however. Markus stated that he just did not have the time to be involved in an $18 million dollar deal.
The biggest point I would like to make is how little damage was caused by discussing this out in the open: the game fell through, at least for the moment, and no effigies were burnt. We might be approaching a time and an industry where these sorts of discussions will not need to be performed in strict secrecy.
Congratulations to Markus Persson and Tim Schafer for being brave or eccentric enough to trust the internet. We are sorry it didn't work out, but wish you luck in the future.
Subject: Editorial, General Tech, Systems, Mobile | February 5, 2013 - 05:10 PM | Scott Michaud
Dell, dude, you're getting a Dell!
So it is official that Dell is going private. Michael Dell, CEO, as well as: Silver Lake, MSD Capital, several banks, and Dell itself will buy back stocks from investors 25% above the January 11th trading price. The whole deal would be worth $24.4 billion USD.
Going private allows the company to make big shifts in their business without answering to investors on a quarterly basis. We can see how being a publicly traded company seems to hinder businesses after they grow beyond what a cash infusion can assist. Even Apple finds it necessary to keep an absolutely gigantic pile of cash to play with, only recently paying dividends to investors.
Also contributing to the buyback, as heavily reported, is a $2 billion USD loan from Microsoft. While it sounds like a lot in isolation, it is only just over 8% of the whole deal. All you really can pull is that it seems like Microsoft supports Dell in their decision and is putting their money where their intentions are.
Subject: Editorial, Cases and Cooling | February 5, 2013 - 12:55 PM | Ryan Shrout
Tagged: seasonic, PSU, power supply, m12ii, giveaway, contest
We know that our readers love to win free stuff, and who can blame you? Building PCs can sometimes be a burden on your wallet and we do our best to help that by showing you the best deals and occasionally having contests like this!
Our good friends at Seasonic wanted to offer up a couple of power supplies for our community and we were obviously excited to facilitate! Here are the goods you can win:
Seasonic M12II SS-850AM 850 watt Power Supply ($130 value - Newegg Link)
Seasonic M12II SS-750AM 750 watt Power Supply ($120 value - Newegg Link)
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The M12II Bronze new models have built in a full protection feature including OCP, OPP,OTP, OVP, SCP & UVP and meet worldwide safety and environmental standards. The all-new M12II-650/750/850 units are the new leaders in the 80 PLUS Bronze category and another great addition to the Seasonic Retail power supply family.
If you are looking to build a new PC or upgrade your current system, either of these two power supplies will make a great backbone for all the other components.
How do you win?
- Visit your favorite PC Perspective pages like our YouTube channel, Facebook page and Twitter account. You should subscribe, like and follow us, you know...if you want to. We'd appreciate it!
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We'll pick a winner on Wednesday the 13th of February, so get your entries in NOW! A big thank you goes out to Seasonic for supporting PC Perspective and for supporting our loyal readers!
Subject: Editorial, General Tech | February 2, 2013 - 06:23 PM | Scott Michaud
Tagged: webkit, w3c, microsoft, internet explorer, html5
Microsoft has been doing their penance for the sins against web developers of the two decades past. The company does not want developers to target specific browsers and opt to include W3C implementations of features if they are available.
Microsoft traditionally fought web standards, forcing developers to implement ActiveX and filters to access advanced features such as opacity. Web developers would program their websites multiple times to account for the... intricacies... of Internet Explorer when compared to virtually every other browser.
Now Google and Apple, rightfully or otherwise (respectively, trollolol), are heavily gaining in popularity. This increase in popularity leads to websites implementing features exclusively for Webkit-based browsers. Internet Explorer is not the browser which gets targeted for advanced effect. If there is Internet Explorer-specific code in sites it is usually workarounds for earlier versions of the browser and only muck up Microsoft's recent standards-compliance by feeding it non-standard junk.
It has been an uphill battle for Microsoft to push users to upgrade their browsers and web developers to upgrade their sites. “modern.IE” is a service which checks for typical incompatibilities and allows for developers to test their site across multiple versions of IE.
Even still, several web technologies are absent in Internet Explorer as they have not been adopted by the W3C. WebGL and WebCL seek to make the web browser into high-performance platform for applications. Microsoft has been vocal about not supporting these Khronos-backed technologies on the grounds of security. Instead of building out web browsers as a cross-platform application platform Microsoft is pushing hard to not get their app marketplace ignored.
I am not sure what Microsoft should fear most: that their app marketplace will be smothered by their competitors, or whether they only manage to win the battle after the war changes theaters. You know what they say, history repeats itself.
Subject: Editorial | January 16, 2013 - 09:41 PM | Josh Walrath
Tagged: ST Ericsson, planar, PD-SOI, L8580, FinFET, FD-SOI, Cortex A9, cortex a15, arm
SOI has been around for some time now, but in partially depleted form (PD-SOI). Quite a few manufacturers have utilized PD-SOI for their products, such as AMD and IBM (probably the two largest producers of SOI based parts). Oddly enough, Intel has shunned SOI wafers altogether. One would expect Intel to spare no expense to have the fastest semiconductor based chips on the market, but SOI did not provide enough advantages for the chip behemoth to outweigh the nearly 10% increase in wafer and production costs. There were certainly quite a few interesting properties to PD-SOI, but Intel was able to find ways around bulk silicon’s limitations. These non-SOI improvements include stress and strain, low-K dialectrics, high-K metal gates, and now 3D FinFET Technology. Intel simply did not need SOI to achieve the performance they were looking for while still using bulk silicon wafers.
Things started looking a bit grim for SOI as a technology a few years back. AMD was starting to back out of utilizing SOI for sub-32 nm products, and IBM was slowly shifting away from producing chips based on their Power technology. PD-SOI’s days seemed numbered. And they are. That is ok though, as the technology will see a massive uptake with the introduction of Fully Depleted SOI wafers. I will not go into the technology in full right now, but expect another article further into the future. I mentioned in a tweet some days ago that in manufacturing, materials are still king. This looks to hold true with FD-SOI.
Intel had to utilize 3D FinFETs on 22 nm because they simply could not get the performance out of bulk silicon and planar structures. There are advantages and disadvantages to these structures. The advantage is that better power characteristics can be attained without using exotic materials all the while keeping bins high, but the disadvantage is the increased complexity of wafer production with such structures. It is arguable that the increase in complexity completely offsets the price premium of a SOI based solution. We have also seen with the Intel process that while power consumption is decreased as compared to the previous 32 nm process, the switching performance vs. power consumption is certainly not optimal. Hence the reason why we have not seen Intel release Ivy Bridge parts that are clocked significantly faster than last generation Sandy Bridge chips.
FD-SOI and planar structures at 22 nm and 20 nm promise the improve power characteristics as compared to bulk/FinFET. It also looks to improve overall power vs. clockspeed as compared to bulk/FinFET. In a nutshell this means better power consumption as well as a jump in clockspeed as compared to previous generations. Gate first designs using FD-SOI could be very good, but industry analysts say that gate last designs could be “spectacular”.
So what does this have to do with ST Ericsson? They are one of the first companies to show a products based on 28 nm FD-SOI technology. The ARM based NovaThore L8580 is a dual Cortex A9 design with the graphics portion being the IMG SGX544. At first glance we would think that ST is behind the ball, as other manufacturers are releasing Cortex A15 parts which improve IPC by a significant amount. Then we start digging into the details.
The fastest Cortex A9 designs that we have seen so far have been clocked around 1.5 GHz. The L8580 can be clocked up to 2.5 GHz. Whatever IPC improvements we see with A15 are soon washed away by the sheer clockspeed advantage that the L8580 has. While it has been rumored that the Tegra 4 will be clocked up to 2 GHz in tablet form, ST is able to get the L8580 to 2.5 GHz in a smartphone. NVIDIA utilizes a 5th core to improve low power performance, but ST was able to get their chip to run at 0.6v in low power mode. This decrease in complexity combined with what appears to be outstanding electrical and thermal characteristics makes this a very interesting device.
The Cortex A9 cores are not the only ones to see an improvement in clockspeed and power consumption. The well known and extensively used SGX544 graphics portion runs at 600 MHz in a handheld device, and is around 20% faster clocked than other comparable parts.
When we add all these things together we have a product that appears to be head and shoulders above current parts from Qualcomm and Samsung. It also appears that these parts are comparable, if not slightly ahead, of the announced next generation of parts from the Cortex A15 crowd. It stands to reason that ST Ericsson will run away with the market and be included in every new handheld sold from now until the first 22/20 nm parts are released? Unfortunately for ST Ericsson, this is not the case. If there was an Achilles Heel to the L8580 it is that of production capabilities. ST Ericsson started production on FD-SOI wafers this past spring, but it was processing hundreds of wafers a month vs. the thousands that are required for full scale production. We can assume that ST Ericsson has improved this situation, but they are not exactly a powerhouse when it comes to manufacturing prowess. They simply do not seem to have the FD-SOI production capabilities to handle orders from more than a handful of cellphone and table manufacturers.
ST Ericsson has a very interesting part, and it certainly looks to prove the capabilities of FD-SOI when compared to competing products being produced on bulk silicon. The Nova Thor L8580 will gain some new customers with its combination of performance and power characteristics, even though it is using the “older” Cortex A9 design. FD-SOI has certainly caught the industrys’ attention. There are more FD-SOI factoids floating around that I want to cover soon, but these will have to wait. For the time being ST Ericsson is on the cutting edge when it comes to SOI and their proof of concept L8580 seems to have exceeded expectations.
Subject: Editorial, General Tech, Systems, Shows and Expos | January 9, 2013 - 02:44 PM | Scott Michaud
Tagged: CES, ces 2013, valve, Steam Box
CES opened with excitement from Xi3 Corporation and their announcement of the Piston. When Gabe Newell spoke with Kotaku at the VGAs he said that we would see Big Picture PCs this year. With word that Xi3 received funding from Valve some of us, including myself, wondered if this Piston was Valve’s “Nexus” Steam Box.
Ben Krasnow, hardware engineer at Valve, comments in the video below about whether we have seen Valve’s canonical Steam Box or if there are any planned announcements for 2013.
Thank you Ben.
There seems to be some discrepancies between statements from Krasnow and Valve Managing Director, Gabe Newell. The major deviation concerns whether the official Steam Box will be based on Linux or another operating system. When interviewed by The Verge, Gabe Newell claimed the official box will be based on Linux with no unclear terms:
We’ll come out with our own and we’ll sell it to consumers by ourselves. That’ll be a Linux box, [and] if you want to install Windows you can. We’re not going to make it hard. This is not some locked box by any stretch of the imagination.
Krasnow in an email discussion with Engadget was somewhat more timid in future plans. The Engadget article was published on the same day as the The Verge interview which makes neither position particularly out of date. His statement:
"The box might be linux-based, but it might not," he continued. "It's true that we are beta-testing Left for Dead 2 on Linux, and have also been public about Steam Big Picture Mode. We are also working on virtual and augmented reality hardware, and also have other hardware projects that have not been disclosed yet, but probably will be in 2013."
At the same point this might all become irrelevant very quickly. As reported yesterday, Gabe Newell in the very same interview seemed to strongly suggest that post-Kepler GPUs will bring virtualization to the consumer market. If that is the case, then the only barrier between Linux and Windows would be for a company to provide a user-friendly virtual machine. Having your host operating system as one or the other would not particularly matter if the user could run gaming applications from the other platform.
PC Perspective's CES 2013 coverage is sponsored by AMD.
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