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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  • Shadow7037932 - Tuesday, April 25, 2017 - link

    It's a first gen release. Do you remember the issues the first gen SSDs had? Do you remember the JMicron stuttering issues? Reply
  • JoeyJoJo123 - Monday, April 24, 2017 - link

    The birth of a new meme. Reply
  • halcyon - Monday, April 24, 2017 - link

    Looks like almost a completely useless interim memory device for almost all workloads (non-server). combine that with a size of 32GB on Kaby Lake, it begs the question : what is the point? Why not release a ready product that has a market niche, and not a slimmed-down beta that is looking for a solution it can't fit? Reply
  • ddriver - Monday, April 24, 2017 - link

    The point is they burned through a mountain of cash to RD this flop and now they are desperately trying to get some of it back. It is a product that doesn't fit in 99% of the market. Thus the solution is to try and shove it anywhere else possible, regardless of how little sense it makes. Reply
  • menting - Monday, April 24, 2017 - link

    you might have forgotten the 1st gen SSDs were about the same, but look at SSDs now. Reply
  • fallaha56 - Tuesday, April 25, 2017 - link

    exactly! so with everyone having learnt that lesson (and having amazing SSDs) Intel has to do better

    this is a pointless product that offers no real advantages and many disadvantages
    Reply
  • carewolf - Friday, June 2, 2017 - link

    I wonder if they still got paid by Intel after revealing that :D Reply
  • tech6 - Monday, April 24, 2017 - link

    The test that I would be interested in is if this technology could be an effective cache is speeding up mainstream SSDs. Reply
  • Sarah Terra - Monday, April 24, 2017 - link

    Perhaps, but better to just wait for pricing to come in line and have the entire disk made from optane or similar. Still can't believe the random writes, this is the biggest jump since the original intel X-25. Basically on any file larger than 4kb you are starting at 4x performance and going waaaaaay up. Reply
  • Twingo - Monday, April 24, 2017 - link

    True, since a SATA based SSD is much cheaper than a NVME drive. I'd like to see the comparison of Optane + 1TB SATA SSD vs 1TB NVME SSD. The 1TB SATA SSD + Optane would be cheaper solution than a 1TB NVME. Reply

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