Live data from Hacker News

Rest in Peace, Optane

specbranch.com

71–80 of 122 posts

Re: Rest in Peace, Optane

#71
post #35

Earlier quoted context omitted.

" The theory that this market exists in any significant way never pans out in practice. " The transition from HDD to SSD technology is a counter example to your claim. It was a drop-in replacement (same SATA interface) and the tech significantly improved performance without any other software modification needed.

Didn't SSD's get a start with laptops and mobile devices? There the advantage of being shock resistant is massive and unsolvable with any other solution. For a superior but new tech to stick, it has to find a viable market to be first self-sustaining, only then can it attack larger and more lucrative markets (Back in those days, PC was probably more lucrative than mobile). Only when SSDs matured enough, did they star…

With SSDs you really feel the performance difference (especially latency) in everyday life. Someone who had experienced an SSD never wanted to go back to a HDD for storing anything but data, since program start-up times are just so much faster when there is no mechanical seeking involved.

The difference between Optane and an SSD was never so striking.

Re: Rest in Peace, Optane

#72
post #64

What was interesting about Optane was that it was kinda an attempt to get rid of disk and ram distinction. You had single device (optane stick) which served as both - ram and disk. After decades of current approach we finally could physically get rid of disks - hdds, ssds or even nvme sticks. https://www.theregister.com/2022/08/01/optane_intel_cancella... >Optane presented a radical, transformative technology but bec…

The problem is optane wasn't as fast as DRAM, nor as cheap as disk. So you still needed the conceptual split anyway, and there wasn't a compelling reason to really use it (OK, I can get a lot of RAM but it's 1/10th the speed of my normal RAM, which will kill both memory latency and memory bandwidth limited applications, which is basically any workload which wants lots of RAM. Or I can get super fast persistent storag…

Hmm, ive seen report by fujitsu that it was fine if used with dram

>Intel Optane persistent memory is blurring the line between DRAM and persistent storage for in-memory computing. Unlike DRAM, Intel Optane persistent memory retains its data if power to the server is lost or the server reboots, but it still provides *near-DRAM performance*. In SAP HANA operation this results in tangible benefits

>Speeds up shutdowns, starts and restarts many times over – significantly reduce system downtime and lower operational costs

 Process more data in real-time with increased memory capacity

 Lower total cost of ownership by transforming the data storage hierarchy

 Improve business continuity with persistent memory and fast data loads at startup

https://sp.ts.fujitsu.com/dmsp/Publications/public/wp-perfor...

Re: Rest in Peace, Optane

#73
post #49

The 1960s memory models of current programming languages were as much a problem as the OSes since since the benefits of persistent programming require slightly different thinking. This reminds me of running Unix on the Cray X-MP. It worked, but was very slow since calling a function stalled these superpipelined machines designed to run FORTRAN really fast.

“very slow” compared to what?

Interactively, it felt like they were slower than even a sun 3. I know this isn't scientific, but I never metered it.

Seymour Cray's CDC machines were fast computers, but IMHO those Cray Corp machines were essentially high performance vector units that happened also to be able to run a bit of control code. I guess it wasn't sexy enough to build a coprocessor, or maybe by then there was enough choice in mainframes that interconnect (which was far from standardized in those days) would have been a barrier.

Re: Rest in Peace, Optane

#74

I think one of the main problems was, that the marketing was especially terrible as they branded both consumer SSDs with an Optane cache as Optane as well as the "real" Optane DC persistent memory, which is put into the appropriate DIMM slots. Another issue may be that Optane DC persistent memory simply was not fast enough to replace non persistent RAM. Still, I hope that another technology will arise, which is byte-…

What do you think of KV SSDs?

Re: Rest in Peace, Optane

#75
I'm also bummed by this and I think it's a major sad example of how poor measurables can really pervert a market (granted, in combination with proprietariness and network effects). SSDs have long been lumped together and measured almost entirely by a few high level sticker numbers that companies themselves loved to trumpet because they are high but are primarily relevant to specific DC/server/(certain)workstation workloads, not the common consumer case. Essentially sequential read, write, and then some random r/w, but all performed with high queue depths and a single block size. Typical users aren't exactly running at QD32 all the time. Storage performance is an area where use cases and edge cases matter, and the measures the industry settled on didn't do a good job of conveying that. Only a few places (like Anandtech back in the day) did a solid regularly job of checking 90/95/99/99.9[n] percentile latency, low queue depths, varied blocks, and you still had to dig into it.

So as a result Optane didn't look on the marketing or even in typical reviews any different then competing NAND-based solutions, or heck would even look slower. And lore developed on the internet even amongst tech folks that it "only made a difference on servers". But I was fortunate enough to grab a few to use for core storage and wow is it noticeable, I've built lots of regular SSD big arrays and they look great at simple patterns with large blocks and then one gets into regular workloads and they absolutely tank, with occasional noticeable blips when garbage collecting or the like gets hit. Better than spinning rust overall, but surprisingly not by much sometimes. Whereas Optane is rock solid consistent no matter what.

Intel and Micron were really dumb in how they tried to use it and push it, but I think it's too bad as well it never really got much popular recognition in terms of differences with NAND. A lot focuses on "closer to RAM" but it was also a better SSD.

Re: Rest in Peace, Optane

#76

What was interesting about Optane was that it was kinda an attempt to get rid of disk and ram distinction. You had single device (optane stick) which served as both - ram and disk. After decades of current approach we finally could physically get rid of disks - hdds, ssds or even nvme sticks. https://www.theregister.com/2022/08/01/optane_intel_cancella... >Optane presented a radical, transformative technology but bec…

Yeah - the article was talking about mmap... but what i wanted was to not have to define persistence boundary. I wanted the entire in-memory state of my program to be persisted - perhaps even duplicated and moved elsewhere

That's an easy way to accumulate data corruption.

It's better to design for unexpected restarts than design for a golden in-memory image which needs to be carefully ported around, have all its connections wired back up, and so on.

You're going to get unexpected restarts anyway. The faster and more reliable you can make recovery from that, it benefits you in the moving use case. The kinds of things you might want to do to enable reliable restart - like retry mechanisms for incoming requests - make migration work too.

Re: Rest in Peace, Optane

#77

What was interesting about Optane was that it was kinda an attempt to get rid of disk and ram distinction. You had single device (optane stick) which served as both - ram and disk. After decades of current approach we finally could physically get rid of disks - hdds, ssds or even nvme sticks. https://www.theregister.com/2022/08/01/optane_intel_cancella... >Optane presented a radical, transformative technology but bec…

Like Itanium, it was one of those Intel projects that was simultaneously too ambitious and not ambitious enough. If Intel really wanted to redesign the Von Neumann architecture, they would have had to be prepared to absorb losses for much longer, way north of a decade. The alternative might have been to focus exclusively on providing SSDs using the new technology and maybe try to segue into this new memory architectu…

I think it will be basically impossible to move away from von Neumann unless you control the entire stack, including OS and software. I don’t even think Apple could do it with Mac, because they are general purpose machines (for now at least). Maybe Apple could do it with iOS devices. Nintendo might be able to pull it off, though people trying port titles from other platforms may no longer try to do so. Because so many AAA titles go between XBox and PS, I don’t think Sony would try.

Re: Rest in Peace, Optane

#78
post #73

Earlier quoted context omitted.

“very slow” compared to what?

Interactively, it felt like they were slower than even a sun 3. I know this isn't scientific, but I never metered it. Seymour Cray's CDC machines were fast computers, but IMHO those Cray Corp machines were essentially high performance vector units that happened also to be able to run a bit of control code. I guess it wasn't sexy enough to build a coprocessor, or maybe by then there was enough choice in mainframes tha…

We weren’t building them to be interactive dedicated mostly-idle personal computers with snappy response times, and that’s not why they were purchased.

Re: Rest in Peace, Optane

#79
post #76

Earlier quoted context omitted.

Yeah - the article was talking about mmap... but what i wanted was to not have to define persistence boundary. I wanted the entire in-memory state of my program to be persisted - perhaps even duplicated and moved elsewhere

That's an easy way to accumulate data corruption. It's better to design for unexpected restarts than design for a golden in-memory image which needs to be carefully ported around, have all its connections wired back up, and so on. You're going to get unexpected restarts anyway. The faster and more reliable you can make recovery from that, it benefits you in the moving use case. The kinds of things you might want to d…

You can design for that. For example, when building a persistent-memory native database engine, you probably need some sort of data versioning anyway - either Postgres style multi-version rows (or some other memory structures) that later need to be vacuumed or Oracle/InnoDB style rollback segments that hold previous values of some modified objects. Then you probably want WAL for efficient replication to other machines and point in time recovery (in case things go wrong or just DB snapshots for dev/test).

Transient & disposable memory structures like keeping track who's logged in or compiled SQL execution plans that facilitate access to the persistent "business data", much of that stuff will need to be in RAM/HBM/CPU cache anyway, for performance reasons and as these things do not necessarily need to persist across a crash/reboot. The data (and likely indexes, etc) need to. But you won't need a buffer cache manager that copies entire blocks around from storage to different places in memory and vice versa. Your giant index or graph could rely just on direct memory pointers instead of physical disk block addresses that need to get read to somewhere in memory and then are accessed via various hashtable lookups & indirect pointers. And you don't have to ship entire 512B-8kB blocks around just to access the next index/graph pointer, just access only the relevant cache line, etc.

With proper design, you'd still have layers of code that take care of coherency, consistency and recovery...

Re: Rest in Peace, Optane

#80

Earlier quoted context omitted.

Didn't SSD's get a start with laptops and mobile devices? There the advantage of being shock resistant is massive and unsolvable with any other solution. For a superior but new tech to stick, it has to find a viable market to be first self-sustaining, only then can it attack larger and more lucrative markets (Back in those days, PC was probably more lucrative than mobile). Only when SSDs matured enough, did they star…

With SSDs you really feel the performance difference (especially latency) in everyday life. Someone who had experienced an SSD never wanted to go back to a HDD for storing anything but data, since program start-up times are just so much faster when there is no mechanical seeking involved. The difference between Optane and an SSD was never so striking.

At least for consumer devices, I think the 'primordial soup' spark of motivation was the original lean and mean netbooks (with the initial push to web apps over running full clients locally, before they became low spec windows laptops), with compact flash ATA adapters to displace HDDs. Power consumption was a factor as well IIRC
Post reply on HN