Samsung had similar claims about v-nand/3D-nand, which they released on their 850 Pro series
This is a completely different technology from NAND.
3D Xpoint memory: Faster-than-flash storage unveiled
31–40 of 99 posts
Re: 3D Xpoint memory: Faster-than-flash storage unveiled
#32Earlier quoted context omitted.
They're claiming three orders of magnitude faster than NAND and three orders of magnitude more durable than NAND, which means you'll still need wear leveling to get it to last for several years, but you apparently won't have the complexity of erase blocks being much larger than writable page size. I do wonder how much it would be slowed down by the kinds of sophisticated error correction SSDs are now relying on.
"Bit-addressable". I don't think this suffers from the same issues that NAND does with successive writes. The other articles I'm seeing after a quick search also suggest a three order of magnitude increase in write endurance.
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 flash is bit addressable but suffers from the same endurance limitations as NAND, because they're fundamentally the same kind of memory cell, just connected differently.
Re: 3D Xpoint memory: Faster-than-flash storage unveiled
#33Earlier quoted context omitted.
They're promising the first chip to be 128Gb, which is where MLC flash is right now. But their die size looks a lot larger than MLC.
Interesting. At 128GB it's definitely practical to put your system partition and applications on it. If you rely heavily on cloud services that would be more than sufficient for most people and even if it isn't you could add an SSD for music and videos. If they release it next year and it turns out well, I can certainly see Apple pulling such a move for the MacBook (Air).
128Gb, not 128GB. You still need quite a few chips to build a usefully large drive.
Re: 3D Xpoint memory: Faster-than-flash storage unveiled
#34Earlier quoted context omitted.
They explicitly mention that they are going to release it next year. Not exactly when next year but it's clear enough of a statement that it will be a public failure, if they don't come out with it. I think that's sufficient to not put it into the vaporware category.
Over the years I have come to realize that unless I can buy something in the nearest BestBuy/Amazon, it is vapor. And also, until then, I would know how much cheaper and better performant it actually is.
It's an official press release from Intel and Micron and the release says that they've begun production, not that they just got it working in a lab.
Performance questions are more valid.
Re: 3D Xpoint memory: Faster-than-flash storage unveiled
#35I assume there are some other disadvantages besides just a high price compared to either DRAM or SSD storage. What are they?
If what they claim is true, it has the potential to be actually cheaper than both DRAM and NAND, based on the density. The biggest disadvantage at the moment is that is so new that we don't know much. What can be read from the announcement: it's not as rewritable as DRAM: only up to 1000 more writes than NAND. It's also slower than DRAM. But it seems better than NAND in all aspects.
It's nowhere near as dense as NAND. It's just a bit denser than DRAM.
Re: 3D Xpoint memory: Faster-than-flash storage unveiled
#36Earlier quoted context omitted.
Interesting. At 128GB it's definitely practical to put your system partition and applications on it. If you rely heavily on cloud services that would be more than sufficient for most people and even if it isn't you could add an SSD for music and videos. If they release it next year and it turns out well, I can certainly see Apple pulling such a move for the MacBook (Air).
128Gb, not 128GB. You still need quite a few chips to build a usefully large drive.
Quite a few being... 8.
Re: 3D Xpoint memory: Faster-than-flash storage unveiled
#37So 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, probably with processor support to allow controlled access without going through the OS for each access.
The great thing about RAM being volatile is that you can reboot and clean up your mess. With persistent storage, things can go gradually downhill.
Re: 3D Xpoint memory: Faster-than-flash storage unveiled
#38Always the same thing. >1000X faster, 1000X cheaper! Then "No, you can't buy one right now, but you will be able to do it "soon". And, no it won't actually be 1000X faster neither 1000X cheaper because blah blah blah..."
... and yet, now we have 10TB hard drives and cheap reliable SSD's on pci. we also have 24 core xeons and x-billion-transistor gpu's. let's not forget fiber at home, 40gig ethernet in the datacenter, and reliable 4G on main st.
clearly, something, somewhere is causing progress to happen, despite your inexplicable inability to see it.
the real problem is people keep making software that gobbles up all these gains.
Re: 3D Xpoint memory: Faster-than-flash storage unveiled
#39So 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 kernel address space. That keeps the part that can mess up the file system’s metadata small.
Re: 3D Xpoint memory: Faster-than-flash storage unveiled
#40So 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…
I think the only distinction you need to make is memory where transactions make sense (user data), and where they don't (program state).
I can see a scenario where opening a file for writing works just like mmap[0] with MAP_PRIVATE, i.e. you get blockwise copy-on-write, except everything will persist as if everything on your filesystem was under a VCS like git.
I reckon just like volume management, encryption and snapshotting has steadily been folded in to the filesystem, so will the VFS and page cache.