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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  • ddriver - Wednesday, April 26, 2017 - link

    It is only natural to have negative sentiments about greedy, lousy corporations because of what they do. It is nothing personal though, I do it because I am a conscious human being. Not cattle. You can throw crapple and moogle into the mix. There is no single good reason to be fond of any corporation. The bigger they are the more damage they do to humanity and the planet as a whole.

    In other news, water is wet!
    Reply
  • eddman - Wednesday, April 26, 2017 - link

    You are not fooling anyone. Reply
  • eddman - Wednesday, April 26, 2017 - link

    ...and you are so blind by your hatred that you dismiss every single thing that these companies do. You are not rational in the slightest but do like to boast about how great you are. Reply
  • Reflex - Tuesday, April 25, 2017 - link

    Nailed it eddman. Because it does not personally solve ddriver's problems, or because it comes from the wrong brand, its an epic disaster. The funny thing here is I agree this is not a revolution, at least not yet, but the incessant bashing and inability to acknowledge that it has its uses and those use cases are likely to only grow demonstrates the bias involved. Reply
  • Reflex - Tuesday, April 25, 2017 - link

    To the insinuation that Optane may somehow be relabeled SLC NAND, I went and did a little research/consultation. All NAND requires writing to blocks, Optane can support bit level writes (expected in DIMM configurations), which is a major advantage over NAND and not technically possible with NAND. It was also pointed out that if Optane was simply disguised SLC, despite the technical impossibility, it would mean that Intel had engaged in financial fraud by materially misrepresenting its technology, capabilities and long-term expectations to investors.

    Thanks to Joel Hruska for looking into it for me.

    More info here: https://arstechnica.com/gadgets/2017/04/intel-opta...

    More from Joel here: https://www.extremetech.com/author/jhruska
    Reply
  • Reflex - Monday, April 24, 2017 - link

    OMG it's the fastest product on the market in its class but because I choose to interpret the early marketing as applying to the first gen product it totally sucks! I refuse to benefit from drastically better performance because Intel *dared* to speak to its potential performance and didn't deliver that in the first product!

    In fact, I am so enraged I'm ripping out all my existing SSD's and replacing them with Quantum Bigfoot drives in protest.
    Reply
  • Drumsticks - Monday, April 24, 2017 - link

    It's probably because Intel dared to do something innovative again, and we can't possibly give credit where it's due, can we? If it was Samsung, I bet it would just be Samsung being Samsung. Slap the blue name on top, and it's cool to criticize whatever you can, even in the face of hard numbers. Make sure you also include an edgy name like "Hypetane" to really drive your point home. Reply
  • Reflex - Monday, April 24, 2017 - link

    To be fair if it were Samsung we'd get a lecture on the oppression of North Korea mixed in there somewhere along with a conspiracy theory about the south being a puppet state not permitted to succeed in the face of America. Reply
  • jabbadap - Monday, April 24, 2017 - link

    Well I don't want to degrade intel's efforts on this. But it's intel/micron co-operation who have engineered this and I would even guess a bit further that science behind this is more micron tech than intels. Reply
  • Drumsticks - Monday, April 24, 2017 - link

    That's fair, and Micron definitely deserves credit as well. I'm sure they'll get their own when QuantX comes out, hopefully sometime this year. I suspect that the R&D was split very evenly, though; Intel has always been good at doing things "well" in the fab; Micron had excelled at doing them "cheaply" which is one reason the venture was reasonably successful. Plus, I feel it would be hard to collaborate on R&D together for 10 years and successfully say "we did this together" to the public, if one side (Micron or Intel) did most of the work. I guess we'll never know, though. Reply

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