Speculation: What physical characteristics do you think 2nd Gen Optane will have?

[cbn]

What physical characteristics do you think 2nd Gen Optane will have?

Multiple votes possible in poll (and users may change votes). Click all options that you think will apply.

 

[cbn]

My guess is that it will have either 4 layers or smaller lithography, but not both.

TSVs: Yes

Material Science improvement (probably not on Second Gen)

Die size: Same if it stays on 20nm.

MLC: Probably not. (Maybe 10% to 20% chance for MLC)

 

[cbn]

Any other physical characteristics that I should have put in the poll?

 

[cbn]

FWIW, I think it is with 3rd Gen Optane that we will see the lithography shrink and other performance improving measures taken. (Reason: 3rd Gen will be the first Optane independently developed by Intel who doesn't have DRAM or other competing new memories acting as conflict of interest like Micron does--see below).

Separate from 3D XPoint, Micron is working on at least one other new memory technology, as an in-house project instead of a collaboration with Intel. This new technology has not been named by Micron, but it will apparently allow for DRAM-like performance, which would be significantly higher than what 3D XPoint can deliver. This unspecified technology also has a clear potential for cost scaling, perhaps through increasing layering. The target it to be a bit slower and cheaper than DRAM, taking into account where DRAM technology is expected to be by the time this new memory comes to market.

 

[IntelUser2000]

I put material science improvement and 4 layers. Those two are what was said to be coming in future XPoint generations.

Also I think there's a possibility 3D XPoint will split into 2 lines. One being more suited to DIMMs and other for fast SSDs.

If what some other slides have said are true it'll also be split like this:

DIMM class 3D XPoint: Faster performance, better endurance, reduced persistence, higher cost
SSD class 3D XPoint: Lower cost, lower endurance, persistence in line with current Optane SSDs

The reduced persistence may mean really, really reduced. So with Optane P4800X drives they say 3 month JEDEC. It may be reduced to days. Perfect for most servers that run all the time and only need reboots or shutting down for hours.

 

[cbn]

A really interesting paper I found on phase change memory (which Optane is said to be based on):

http://poplab.stanford.edu/pdfs/Raoux-PCMreview-mrsbull14.pdf

Here is one of the parts I liked:

Using PCM to replace DRAM is a formidable challenge, because very fast switching times in the nanoseconds range and extremely high cycle numbers of ∼10^16 present a combination of requirements that have not been achieved by phase changematerials. DRAM replacement is a special case since DRAM is a volatile memory, whereas PCM is a non-volatile memory.
If PCM were to achieve DRAM-like performance, it would open up possibilities to realize completely new computer architectures. Very fast switching times have been achieved for several phase change materials, including Ge2Sb2Te5 and GeTe in actual PCM devices. The high cycle number remains an enormous challenge, but it appears that scaling to smaller dimensions of the phase change material is beneficial for cycling. Data measured on highly scaled PCM cells using an Sb-rich Ge-Sb-Te phase change material demonstrated 10^11 cycles under accelerated testing conditions using a switching power of 45 pJ, which leads to an extrapolated cycle number of 6.5 × 10^15 cycles under normal switching conditions using 3.6 pJ.

So lithography shrink + materials science could really improve things.

P.S. I am guessing multi-bit per cell (for applications other than DRAM replacement) will come after these improvements.

 

[cbn]

While I did vote (back in October 2018) that die size would not change, I do wonder if Gen 2 Optane takes a page or two out of IMFT Gen 2 3D NAND's playbook?

Remember how IMFT Gen 1 3D NAND only came in one size, a big 168mm2 32L 256Gb MLC/384Gb TLC....but Gen 2 started off with a small 58mm2 64L 256Gb TLC die:

https://www.techinsights.com/techno...st-reports/intel-micron-64l-3d-nand-analysis/

With a 64L 512Gb TLC die and a 64L 768Gb TLC/1024Gb QLC die that followed.

Maybe Gen 2 3DXpoint does the same thing? (ie, start of with a small die, follow up with a medium die and finish up with a large die)

If true, then we would have a much different landscape for Optane (on the consumer front).

For one thing writes would be a whole better without needing high capacities. That alone could put a 16GB Optane made with two Gen 2 64Gb 3DXpoint into the same write ballpark we saw with the 58GB 800p (reason: parallelism per GB increases by four because a (estimated) 51.5mm2 Gen 2 64Gb die has the same amount of layers as two Gen 1 128Gb dies). That would be excellent! Likewise a 32GB Optane made up of four 64Gb Gen 2 3DXpoint dies could potentially be double that in writes (controller permitting).

Also, I do wonder if small die will make it more likely that we will see 3DXpoint replace DRAM buffer (while adding cache) in consumer SSD controllers? Replace DRAM in RAID cards?

P.S. In the past I was confused on why the Optane M15 would use 16GB Gen 1 Optane with PCIe 3.0 x4, but maybe Intel wants the extra links because small die Gen 2 will boost Sequential Read even at such a low capacity? (With this noted I am still concerned about PCIe 3.0 x4 increasing latency over PCIe 3.0 x2)