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3D Xpoint memory: Faster-than-flash storage unveiled

bbc.com

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Re: 3D Xpoint memory: Faster-than-flash storage unveiled

#71

Post by ncr100 »

throw1111 wrote: post #62
russdill wrote: post #52

Earlier quoted context omitted.

Forward looking article from June with tons of analysis http://seekingalpha.com/article/3253655-intel-and-micron-the...

No, apparently it's not PCM. >While they did not specifically state it, it looks to be phase change memory ( edit at the Q&A Intel stated this is not Phase Change). Source: http://www.pcper.com/news/Storage/Breaking-Intel-and-Micron-...

The video presentation mentioned "resistive". I'm not a memory nerd. Does that fact from their disclosure help at all narrow what this type of memory can be best categorized as?

https://intel-micron-webcast.intel.com/webcast

Re: 3D Xpoint memory: Faster-than-flash storage unveiled

#72

Post by russdill »

ncr100 wrote: post #71
throw1111 wrote: post #62

Earlier quoted context omitted.

No, apparently it's not PCM. >While they did not specifically state it, it looks to be phase change memory ( edit at the Q&A Intel stated this is not Phase Change). Source: http://www.pcper.com/news/Storage/Breaking-Intel-and-Micron-...

The video presentation mentioned "resistive". I'm not a memory nerd. Does that fact from their disclosure help at all narrow what this type of memory can be best categorized as? https://intel-micron-webcast.intel.com/webcast

There is an entire family of memory elements who's resistance is modified in order to store data. RRAM/ReRAM, CBRAM, PCM, MRAM, as well as many others.

Re: 3D Xpoint memory: Faster-than-flash storage unveiled

#73

Post by listic »

Looks like this news item is made up from recent Intel's press release [1] and quite a bit of hand-waving. Take, for example, a claim that 'it would radically increase the number of people that could be supported for the same price'. We already have E7 series Xeons that support up to 1.5TB of RAM [2] (is it per socket? there can be up to 8 sockets per server) At that point, surely we would be constrained by processing and I/O, not RAM.

[1] http://newsroom.intel.com/community/intel_newsroom/blog/2015...

[2] http://ark.intel.com/products/84685/Intel-Xeon-Processor-E7-...

Re: 3D Xpoint memory: Faster-than-flash storage unveiled

#74

Post by wtallis »

davrosthedalek wrote: post #45
wtallis wrote: post #32

Earlier quoted context omitted.

Yes, if you read what I wrote I mentioned the three orders of magnitude increase in write endurance as compared with NAND. But when paired with the three orders of magnitude increase in performance, that means it takes the same number of hours to burn it out. And a NAND device without wear leveling can be burned out in less than a day of heavy use. Bit addressability has absolutely nothing to do with endurance. NOR f…

The thing about bit addressability is not completely true. If you can address memory only in pages, you can have quite a large write amplification, depending on the access pattern. A single byte written may count as $PAGESIZE "written data".

A lack of bit addressability means that hammering one bit would burn out a whole word/page, but it doesn't affect how many cycles it takes to reach that burn-out point, unless you've got wear leveling.

In practice, if you burn out any one bit, you need to retire a chunk of the array at least as large as a cache line. And it's not likely that you'll actually be able to directly hammer a single bit, because the endurance is still low enough to require ECC.

Re: 3D Xpoint memory: Faster-than-flash storage unveiled

#75

Post by wmf »

kristianp wrote: post #68

This article is so thin on details. "3D XPoint works by changing the properties of the material that makes up its memory cells to either having a high resistance to electricity to represent a one or a low resistance to represent a zero." How does it do that?

The BBC isn't EE Times and they're never going to be. Also, Intel is going out of their way to avoid providing many details, so in this case it isn't the press who's dumbing it down.

Re: 3D Xpoint memory: Faster-than-flash storage unveiled

#76

Post by simpsond »

p1esk wrote: post #47
simpsond wrote: post #24

Earlier quoted context omitted.

Do memristors read or write based on the applied voltage? I noticed that in some of the intel marketing material.

How else would you do read/write?

I'm not familiar with the physics of memristors or storage in general. I was wondering if a single line is used to read and write, increasing the voltage on write to change the state.

Re: 3D Xpoint memory: Faster-than-flash storage unveiled

#77

Post by stellarhopper »

Someone wrote: post #39
Animats wrote: post #37

So what do we do with it? We have two models of storage - volatile working storage, and things that simulate disk drives. It's not clear what to do with persistent randomly addressable storage at DRAM speed. Having to go through an OS and a file system to access a few bytes kills the performance advantage of such devices. Making the device look like RAM makes it too easy to mess up. We need something in between, prob…

Use the MMU to keep the fast non-volatile RAM out of both application and kernel memory, put a traditional RAM disk file system on the fast non-volatile RAM, and let mmap truly map blocks of files into address spaces, instead of demand-paging it in. That probably is not the best one can do, but it is simple, and may be fairly easy to get ‘right’ if you put the code handling the file system part into a secondary kerne…

DAX, which is already in new kernels, provides something like this.

https://lwn.net/Articles/610174/

Re: 3D Xpoint memory: Faster-than-flash storage unveiled

#78

Post by MaysonL »

mmf wrote: post #42

I did research in the field from 2008 to 2013. The claims are always the same: faster than flash, denser than dram, lower power than both. Here's how to spot BS: first, the density claims are immaterial until they prove yield at a technology node same as dram's today. There are multiple billions investment between 180nm and high yield (and low mask count) 2xnm, no matter how cool is the new memory technology. Second,…

How often does the BS include "going into production" and "sampling later this year"?

Re: 3D Xpoint memory: Faster-than-flash storage unveiled

#79

Post by kragen »

simpsond wrote: post #76
p1esk wrote: post #47

Earlier quoted context omitted.

How else would you do read/write?

I'm not familiar with the physics of memristors or storage in general. I was wondering if a single line is used to read and write, increasing the voltage on write to change the state.

Apparently a few different things have been called "memristors", but at least some of them have a resistance that depends upon the integral of current through them into the infinite past. DC current one way to write a 1, the other way to write a 0, and AC current to nondestructively read, I guess. Typically this works through ion migration in the material, and I suspect that resulted in abysmal endurance, putting an end to the promise of memristors.

Re: 3D Xpoint memory: Faster-than-flash storage unveiled

#80

Post by mmf »

MaysonL wrote: post #78
mmf wrote: post #42

I did research in the field from 2008 to 2013. The claims are always the same: faster than flash, denser than dram, lower power than both. Here's how to spot BS: first, the density claims are immaterial until they prove yield at a technology node same as dram's today. There are multiple billions investment between 180nm and high yield (and low mask count) 2xnm, no matter how cool is the new memory technology. Second,…

How often does the BS include "going into production" and "sampling later this year"?

Here:

BS: "going into production this year"

Possibly not BS: "going into production this year at 2x nam technology node with a y Gb part"

Many nvm memory technologies, including mram and PCM have been "in production" for quite many years, with << 1Gb parts on old technology nodes, that is.

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