> One of the things that drove mass SSD adoption was the experience was plainly better. Even the most illiterate user could see how fucking fast an SSD machine booted and how much more responsive they were.

> SSD to Optane? There's no practical difference.

No, that's false. That's true of NVMe in general but Optane specifically is really good at the low-queue-depth random-4k workloads that characterize consumer use-cases.

Optane actually is extremely fast at things like OS patches that normally take a few minutes even on NVMe flash let alone sata. They boot faster, applications launch faster, etc. Normally those things don't have lots of parallel threads running so queue depth is low and flash doesn't perform very well (as in, SATA and NVMe are nearly indistinguishable), but Optane really helps.

Is that worth paying 10x as much for? No, probably not, but that's the real problem, not the general lack of performance. Optane is actually noticeable specifically for being the first thing that actually provides a noticeable improvement above and beyond SATA SSDs for consumer use-cases. It's just also too expensive to be justifiable.

Although "client computing" is still the largest source of Intel revenue, and its scale was what made the x86 architecture able to crush legacy server architectures, I think Intel takes it for granted relative to the data center.

It would have been very interesting to see an "all Optane" tablet device but it would have been hard to make work: a modest amount of storage would be affordable but it would take a clean sheet OS to maximize performance and economics.

I was skeptical about Optane DIMMs.

Optane SSDs were the fastest SSD you'd ever seen, but the DIMMS were the slowest you'd seen in a while. Although they were faster than Optane SSDs, they were slower than RAM if you replaced RAM 1-1. Optane was denser and cheaper than ordinary RAM so you could pack your machine with a huge quantity of slow RAM.

If access patterns and cache behavior permit, you could build systems of a certain problem size that perform well with Optane. Advanced programming techniques can help.

For every big problem there are many little problems (don't need Optane) and some problems are too big for Optane. Many problems in the size range for Optane can be implemented to conserve RAM and have access patterns that stream well to mass storage. Thus Optane faced fierce competition.

In practical terms the only real use for Optane DIMMs was very high capacity RAM systems. Optane let you get 512GB in a stick when LRDIMM was 128GB. And of course you can still go multisocket etc too. So you run the same software, but in large-VRAM scenarios that couldn't be handled optimally by LRDIMMs without paging. Things like SAP HANA and so on.

But a system that only makes sense in super high end configurations is setting an uphill battle for itself. You can't even put together a demo machine without using one of a handful of processors at the top of Intel's stack, how do you even demo that to your boss as a concept? And in the end the commodity solutions just ended up outpacing it at lower cost, flash still sucks at random but it's generally fine and people don't want to pay the extra $500 for optane on their 1tb drive.

Software getting entirely rewritten for NVRAM is a pipe dream lol. Maybe you could have defined a "high range" ala HIMEM that is persistent across boots and will never be allocated, just used it as a block device so your SAP database would never unload, but, yeah, there are non-trivial problems.

> and its scale was what made the x86 architecture able to crush legacy server architectures, I think Intel takes it for granted relative to the data center

This is true; the reason is that the margins on the data center chips are what keeps the lights on.

I think one of the major missing factors is lack of OS support for the sorts of features that NVDIMM could potentially bring to the table. Super-fast wake from deep hibernation is just a starting point, the real work is re-writing every line of code written since the dawn of computing which starts from the two assumptions "one kind of storage is persistent and slow" and "the other kind of storage is volatile and fast".

HPE made noise about challenging those assumptions with The Machine but predictably lost interest as their own memristor technology lost steam.

> What could have saved it?

Persistent memory was/is a big topic in the database research world. The idea was that you would not need to worry about ACID since all your data is still there in the event of a power loss/crash. It would massively simplify database code.

However as it turns out... persistent memory doesn't buy you all that much. You still effectively need a replay log to restore the state you were in before a crash event, and you still need all the restoration code. In the end it in most systems it just behaved as a very fast (and expensive) SSD. The benefits vs. price just wasn't there as a modern DB setup on a fast SSD + more RAM would get you much more performance per dollar.

What you'd really need is transactional memory, not just persistent memory. And you'd need a database engine written completely from the ground up to use this memory. Probably several hundred KLoC of tricky code (and all the joys that come with parallel programming), targeted at hardware that doesn't even exist yet. Sounds very expensive and risky to me.

I think eventually we'll see something in this line of technology become commercially available. But I'm not surprised that Intel pulled out.

  > " And you'd need a database engine written completely from the ground up to use this memory."

You mean like the one from one of CMU's research projects, that Pavlo et al have written about?

https://db.cs.cmu.edu/projects/nvm/

  "How to Build a Non-Volatile Memory Database Management System," in Proceedings of the 2017 ACM International Conference on Management of Data, 2017

  "Spitfire: A Three-Tier Buffer Manager for Volatile and Non-Volatile Memory," in Proceedings of the 2021 International Conference on Management of Data, 2021, pp. 2195-2207.

Optane was pretty great for fs and db logs / journals.

That was pretty much its killer (practical) use case.

What's more, Optane was sold as... a cache to have in front of your spinning rust. In an age where SSDs were cheap enough that you could just get a few TB of SSD and have all your data access sped up, not just what happens to be in cache.

It could have made a big difference but it was adoption that was the problem. Swapping an SSD from a HDD is very easy and straight forward for most people - SATA cables are also well designed and easy to understand. Its almost like a USB cable in an L shape.

Completely changing the format? That is a huge obstacle.

NVME SSD's also came along soon enough we got something that was much, much faster than SATA SSD's and eventually I think it just became clear it was diminishing returns. That being said I am still hoping for an Optane replacement.

They should have sold it as level 4 cache

you mean swap drive ?

That's what I used the <$10 16gb Optane sticks for, when I had a batch of terrible small zero cache SSDs. Just to extend the performant life of the hardware I was stuck with. Worked ok.