Intel's Caching History

Intel's first attempt at using solid-state memory for caching in consumer systems was the Intel Turbo Memory, a mini-PCIe card with 1GB of flash to be used by the then-new Windows Vista features Ready Drive and Ready Boost. Promoted as part of the Intel Centrino platform, Turbo Memory was more or less a complete failure. The cache it provided was far too small and too slow—sequential writes in particular were much slower than a hard drive. Applications were seldom significantly faster, though in systems short on RAM, Turbo Memory made swapping less painfully slow. Battery life could sometimes be extended by allowing the hard drive to spend more time spun down in idle. Overall, most OEMs were not interested in adding more than $100 to a system for Turbo Memory.

Intel's next attempt at caching came as SSDs were moving into the mainstream consumer market. The Z68 chipset for Sandy Bridge processors added Smart Response Technology (SRT), a SSD caching mode for Intel's Rapid Storage Technology (RST) drivers. SRT could be used with any SATA SSD but cache sizes were limited to 64GB. Intel produced the SSD 311 and later SSD 313 with low capacity but relatively high performance SLC NAND flash as caching-optimized SSDs. These SSDs started at $100 and had to compete against MLC SSDs that offered multiple times the capacity for the same price—enough that the MLC SSDs were starting to become reasonable options for every general-purpose storage without any hard drive.

Smart Response Technology worked as advertised but was very unpopular with OEMs, and it didn't really catch on as an aftermarket upgrade among enthusiasts. The rapidly dropping prices and increasing capacities of SSDs made all-flash configurations more and more affordable, while SSD caching still required extra work to set up and small cache sizes meant heavy users would still frequently experience uncached application launches and file loads.

Intel's caching solution for Optane Memory is not simply a re-use of the existing Smart Response Technology caching feature of their Rapid Storage Technology drivers. It relies on the same NVMe remapping feature added to Skylake chipsets to support NVMe RAID, but the caching algorithms are tuned for Optane. The Optane Memory software can be downloaded and installed separately without including the rest of the RST features.

Optane Memory caching has quite a few restrictions: it is only supported with Kaby Lake processors and it requires a 200-series chipset or a HM175, QM175 or CM238 mobile chipset. Only Core i3, i5 and i7 processors are supported; Celeron and Pentium parts are excluded. Windows 10 64-bit is the only supported operating system. The Optane Memory module must be installed in a M.2 slot that connects to PCIe lanes provided by the chipset, and some motherboards will also have M.2 slots that do not support Optane Caching or RST RAID. The drive being cached must be SATA, not NVMe, and only the boot volume can be cached. Lastly, the motherboard firmware must have Optane Memory support to boot the cached volume. Motherboards that have the necessary firmware features will feature a UEFI tool to unpair the Optane Memory cache device from the backing device being cached, but this can also be performed with the Windows software.

Many of these restrictions are arbitrary and software enforced. The only genuine hardware requirement seems to be a Skylake 100-series or later chipset. The release notes for the final production release of the Optane Memory and RST drivers even includes in the list of fixed issues the removal of the ability to enable Optane caching with a non-Optane NVMe cache device, and the ability to turn on Optane caching with a Skylake processor in a 200-series motherboard. Don't be surprised if these drivers get hacked to provide Optane caching on any Skylake system that can do NVMe RAID with Intel RST.

Intel's latest caching solution is not being pitched as a way of increasing performance in high-end systems; for that, they'll have full-size Optane SSDs for the prosumer market later this year. Instead, Optane Memory is intended to provide a boost for systems that still rely on a mechanical hard drive. It can be used to cache access to a SATA SSD or hybrid drive, but don't expect any OEMs to ship such a configuration—it won't be cost-effective. The goal of Optane Memory is to bring hard drive systems up to SSD levels of performance for a modest extra cost and without sacrificing total capacity.

Introduction Testing Optane Memory
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  • name99 - Tuesday, April 25, 2017 - link

    Why are you so sure you understand the technology? Intel has told us nothing about how it works.
    What we have are
    - a bunch of promises from Intel that are DRAMATICALLY not met
    - an exceptionally lousy (expensive, low capacity) product being sold.
    You can interpret these in many ways, but the interpretation that "Intel over promised and dramatically underdelivered" is certainly every bit as legit as the interpretation "just wait, the next version (which ships when?) will be super-awesome".

    If Optane is capable TODAY of density comparable to NAND, then why ship such a lousy capacity? And if it's not capable, then what makes you so sure that it can reach NAND density? Getting 3D-NAND to work was not a cheap exercise. Does Intel have the stomach (and the project management skills) to last till that point, especially given that the PoS that they're shipping today ain't gonna generate enough of a revenue stream to pay for the electric bill of the Optane team while they take however long they need to get out the next generation.
    Reply
  • emn13 - Tuesday, April 25, 2017 - link

    Intel hasn't confirmed what it is, but AFAICT all the signs point to xpoint being phase-change ram, or at least very similar to it. Which still leaves a lot of wiggle room, of course. Reply
  • ddriver - Tuesday, April 25, 2017 - link

    IIRC they have explicitly denied xpoint being PCM. But then again, who would ever trust a corporate entity, and why? Reply
  • Cellar - Tuesday, April 25, 2017 - link

    Implying Intel would only use only the revenue of Optane to fund their next generation of Optane. You forget how much profit they make milking out their Processors? *Insert Woody Harrelson wiping tears away with money gif* Reply
  • name99 - Tuesday, April 25, 2017 - link

    Be careful. What he's criticizing is the HYPE (ie Intel's business plan for this technology) rather than the technology itself, and in that respect he is basically correct. It's hard to see what more Intel could have done to give this technology a bad name.

    - We start with the ridiculous expectations that were made for it. Most importantly the impression given that the RAM-REPLACEMENT version (which is what actually changes things, not a faster SSD) was just around the corner.

    - Then we get this attempt to sell to the consumer market a product that makes ZERO sense for consumers along any dimension. The product may have a place in enterprise (where there's often value in exceptionally fast, albeit expensive, particular types of storage), but for consumers there's nothing of value here. Seriously, ignore the numbers, think EXPERIENCE. In what way is the Optane+hard drive experience better than the larger SSD+hard drive or even large SSD and no hard drive experience at the same price points. What, in the CONSUMER experience, takes advantage of the particular strengths of Optane?

    - Then we get this idiotic power management nonsense, which reduces the value even further for a certain (now larger than desktop) segment of mobile computing

    - And the enforced tying of the whole thing to particular Intel chipsets just shrinks the potential market even further. For example --- you know who's always investigating potential storage solutions and how they could be faster? Apple. It is conceivable (obviously in the absence of data none of us knows, and Intel won't provide the data) that a fusion drive consisting of, say, 4GB of Optane fused to an iPhone or iPad's 64 or 128 or 256GB could have advantages in terms of either performance or power. (I'm thinking particularly for power in terms of allowing small writes to coalesce in the Optane.)
    But Intel seems utterly uninterested in investigating any sort of market outside the tiny tiny market it has defined.

    Maybe Optane has the POTENTIAL to be great tech in three years. (Who knows since, as I said, right know what it ACTUALLY is is a secret, along with all its real full spectrum of characteristics).
    But as a product launch, this is a disaster. Worse than all those previous Intel disasters whose names you've forgotten like ViiV or Intel Play or the Intel Personal Audio Player 3000 or the Intel Dot.Station.
    Reply
  • Reflex - Tuesday, April 25, 2017 - link

    Meanwhile in the server space we are pretty happy with what we've seen so far. I get that its not the holy grail you expected, but honestly I didn't read Intel's early info as an expectation that gen1 would be all things to all people and revolutionize the industry. What I saw, and what was delivered, was a path forward past the world of NAND and many of its limitations, with the potential to do more down the road.

    Today, in low volume and limited form factors it likely will sell all that Intel can produce. My guess is that it will continue to move into the broader space as it improves incrementally generation over generation, like most new memory products have done. Honestly the greatest accomplishment here is Intel and Micron finally introducing a new memory type, at production quantity, with a reasonable cost for its initial markets. We've spent years hearing about phase-change, racetrack, memrister, MRAM and on and on, and nobody has managed to introduce anything at volume since NAND. This is a major milestone, and hopefully it touches off a race between Optane and other technologies that have been in the permanent 3-5 year bucket for a decade plus.
    Reply
  • ddriver - Tuesday, April 25, 2017 - link

    Yeah, I bet you are offering hypetane boards by the dozens LOL. But shouldn't it be more like "in the _servers that don't serve anyone_ space" since in order to take advantage of them low queue depth transfers and latencies, such a s "server" would have to serve what, like a client or two?

    I don't claim to be a "server specialist" like you apparently do, but I'd say if a server doesn't have a good saturation, they either your business sucks and you don't have any clients or you have more servers than you need and should cut back until you get a good saturation.

    To what kind of servers is it that beneficial to shave off a few microseconds of data access? And again, only in low queue depth loads? I'd understand if hypetane stayed equally responsive regardless of the load, but as the load increases we see it dwindling down to the performance of available nand SSDs. Which means you won't be saving on say query time when the system is actually busy, and when the system is not it will be snappy enough as it is, without magical hypetane storage. After all, servers serve networks, and even local networks are slow enough to completely mask out them "tremendous" SSD latencies. And if we are talking an "internet" server, then the network latency is much, much worse than that.

    You also evidently don't understand how the industry works. It is never about "the best thing that can be done", it is always about "the most profitable thing that can be done". As I've repeated many times, even NAND flash can be made tremendously faster, in terms of both latency and bandwidth, it is perfectly possible today and it has been technologically possible for years. Much like it has been possible to make cars that go 200 MPH, yet we only see a tiny fraction of the cars that are actually capable to make that speed. There has been a small but steady market for mram, but that's a niche product, it will never be mainstream because of technological limitations. It is pretty much the same thing with hypetane, regardless of how much intel are trying to shove it to consumers in useless product forms, it only makes sense in an extremely narrow niche. And it doesn't owe its performance to its "new memory type" but to its improved controller, and even then, its performance doesn't come anywhere close to what good old SLC is capable of technologically as a storage medium, which one should not confuse with a compete product stack.

    The x25-e was launched almost 10 years ago. And its controller was very much "with the times" which is the reason the drive does a rather meager 250/170 mb/s. Yet even back then its latency was around 80 microseconds, with its "latest and greatest" hypetane struggling to beat that by a single order of magnitude 10 years later. Yet technologically the SLC PE cycle can go as low as 200 nanoseconds, which is 50 times better than hypetane and 400 times better than what the last pure SLC SSD controller was capable of.

    No wonder the industry abandoned SLC - it was and still is too good not only for consumers but also for the enterprise. Which begs the question, with the SLC trump card being available for over a decade why would intel and micron waste money on researching a new media. And whether they really did that, or simply took good old SLC, smeared a bunch of lies, hype and cheap PR on it to step forward and say "here, we did something new".

    I mean come on, when was the last time intel made something new? Oh that's right, back when they made netburst, and it ended up a huge flop. And then, where did the rescue come from? Something radically new? Nope, they got back to the same old tried and true, and improved instead of trying to innovate. Which is also what this current situation looks like.

    I can honestly think of no better reason to be so secretive about the "amazing new xpoint", unless it actually isn't neither amazing, nor new, nor xpoint. I mean if it s a "tech secret" I don't see how they shouldn't be able to protect their IP via patents, I mean if it really is something new, it is not like they are short on the money it will take to patent it. So there is no good reason to keep it such a secret other than the intent to cultivate mystery over something that is not mysterious at all.
    Reply
  • eddman - Tuesday, April 25, 2017 - link

    This is what happens when people let their personal feelings get in the way.

    "Even if they cure cancer, they still suck and I hate them"
    Reply
  • ddriver - Tuesday, April 25, 2017 - link

    Except it doesn't cure cancer. And I'd say it is always better to prevent cancer than to have the destructive treatment leave you a diminished being. Reply
  • eddman - Tuesday, April 25, 2017 - link

    Just admit you have a personal hatred towards MS, intel and nvidia, no matter what they do, and be done with it. It's beyond obvious. Reply

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