Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Rest in Peace, Optane

specbranch.com

Post reply on HN
Print view View original

61–70 of 122 posts

Re: Rest in Peace, Optane

#61

Post by rwmj »

eternityforest wrote: post #50
DeathArrow wrote: post #36

Earlier quoted context omitted.

I think the idea is to have large persistent storage with the speeds of RAM. Everything would open instantly.

That would be useful, but it wouldn't really replace RAM, or, if it did, we'd probably still wipe it every boot, to be in a known state. Outside of some specialized database applications, having an entire program running right in persistent memory seems like a bad idea. And even then, I'm assuming databases would still want strong separation between persistent stuff and stuff that can be restarted any moment, to mini…

Even if you don't use it for state, there's still a lot of code and read-only data that could benefit from being executed directly out of Optane.

Re: Rest in Peace, Optane

#62

Post by mike_hock »

hardware2win wrote: post #6

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 architecture 10 years later. Like Itanium should have initially focused on beating competing x86_32 chips of the era in benchmarks and ship the new ISA as an afterthought.

Thank you, Intel, for trying to push the envelope, though.

Re: Rest in Peace, Optane

#64

Post by rcxdude »

hardware2win wrote: post #6

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 storage with high durability but much higher cost, which basically makes it good for a persistent cache but not that much else, considering SSDs are now similarly fast even though their durability is not as good). It wasn't sunk by a stuck-in-the-mud way of thinking about memory versus disk, it was sunk because the tech never got good enough to actually achieve their ambitions.

Re: Rest in Peace, Optane

#65

Post by pklausler »

gumby wrote: 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?

Re: Rest in Peace, Optane

#66

Post by waxali9815 »

I'd like to offer my experience with the consumer-targeted Optane devices. I had a laptop that I replaced about 2 or 3 years ago, that had a hybrid 512GB HDD + 32GB Optane storage.

It was a massive headache for me. One fine day my laptop ran into the common Windows issue of 100% disk utilization. I tried all the common fixes to no avail, and at some point I remembered my disk had some funky new tech called Optane. I disabled Optane through its software and was able to directly access the underlying HDD. I checked the fragmentation level for the HDD, lo and behold it was fragmented to oblivion.

Turns out because Windows treats Optane disks as SSDs even though I actually had an underlying HDD, my HDD was simply not defragmented by the OS. After a few rounds of installing and uninstalling large games, the HDD was in an unusable state with regards to fragmentation.

I did a short write-up PSA on r/Windows10, and apparently the issue was widespread enough that my post helped about 10 people in the comments. Thinking back, this whole series of events is partially the reason why I moved from being a non-technical person to a (somewhat) technical one. Good times.

Re: Rest in Peace, Optane

#67

Post by zozbot234 »

tanelpoder wrote: post #26
zinodaur wrote: post #14

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

mmap on Optane direct-access-aware (DAX) filesystems like EXT4/XFS now, is not like mmap on block devices where the OS gets in your way and pages stuff in from disk and (maybe) later syncs it back to persistent storage. Optane is the persistent storage, it's just usable/addressable as regular RAM as it's plugged in to DIMM slots. And in the later Xeon architecture (Xeon Scalable 3rd gen, I think), intel expanded the…

> mmap on Optane direct-access-aware (DAX) filesystems like EXT4/XFS now, is not like mmap on block devices where the OS gets in your way and pages stuff in from disk

Yes, the real case for Optane memory is that, supposedly, you don't have to fsync(). And insisting on proper fsync() tends to tank the performance of even the fastest NVMe SSD's. So the argument for a real, transformative performance improvement is there.

Re: Rest in Peace, Optane

#68

Post by NikkiA »

alpaca128 wrote: post #60
masklinn wrote: post #59

Earlier quoted context omitted.

Intel and AMD also do support unified memory for their integrated graphics. It’s been a while since you needed a statically cordoned-off area of main memory (“shared memory”) for the iGPU to work. Consoles have been using unified memory since the 8th gen (PS4/XB1/Switch, kinda sorta even WiiU). And NVidia has CUDA unified-memory slide decks going back at least 5 years.

The Xbox360 already had unified memory too. That gave it a slight edge compared to the PS3 in the long term because it was more flexible compared to a fixed 50:50 split.

The original xbox before it too.

Re: Rest in Peace, Optane

#69

Post by lichtenberger »

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-addressable and persistent/durable. I think it could radically change the design of database systems again. You wouldn't have to have a page cache / buffer manager, which retrieves same sized blocks (or multiples of blocks) for instance. You probably wouldn't even need serialization/deserialization to disk.

It would be great if it'd be possible to for instance read 512byte blocks from disk with current SSDs, but I guess the block overhead for meta data might be too big.

Re: Rest in Peace, Optane

#70

Post by rcxdude »

tanelpoder wrote: post #52
eternityforest wrote: post #27

Why was everyone so obsessed with the idea of Optane as universal memory? From a consumer perspective, it was a fast small SSD that doesn't wear out. That was enough to justify it's value at the prices it went for(Or at least it seems like it, I never personally used it). It didn't need any radical rethink of computing to be worth it. I'm not even a fan of the nonvolatile RAM idea. Rebooting is often the first thing…

As it's part of the memory domain, not some external block device, the CPU caches can cache it (64B cache line sizes) and maintain cache coherency across CPUs, NUMA nodes (and soon with CXL 3.x ?) across memory pools shared by many servers. So your programming model will be just using CPU loads & stores to access the individual bytes you need directly from the Optane storage, instead of having to do some 512B or 4kB…

There's not much here that requires optane as the underlying storage tech, though. CPUs can already treat PCIe devices as memory, and do the same caching work underneath it. Most modern SSDs are alreadying using PCIe, it's just the protocol on top of it doesn't support mapping the contents of the disk to memory like this, but there's no real reason they couldn't.
Post reply on HN