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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  • BrokenCrayons - Monday, April 24, 2017 - link

    A desktop Linux distro would fit nicely on it with room for local file storage. I've lived pretty happily with a netbook that had a 32GB compact flash card on a 2.5 inch SATA adapter that had Linux Mint 17.3 on it. The OS and default applications used less than 8GB of space. I didn't give it a swap partition since 2GB was more than enough RAM under Linux (system was idle at less than 200MB and I never saw it demand more than 1.2GB when I was multi-tasking). As such, there was lots of space to store my music, books, and pics of my cat. Reply
  • ddriver - Monday, April 24, 2017 - link

    And imagine how well DOS will run. And you have ample space for application and data storage. 32 gigs - that's what dreams were made of in the early 90s. Your music, books and cat pics are just icing on the cake. Let me guess, 64 kbit mp3s right? Reply
  • BrokenCrayons - Monday, April 24, 2017 - link

    I'm impressed at the level of your insecurity. Reply
  • mkozakewich - Thursday, April 27, 2017 - link

    I've made the decision to never read any comment with his name above, but sometimes I accidentally miss it. Reply
  • DanNeely - Monday, April 24, 2017 - link

    Looking at the size of it, I'm wondering why they didn't make a 48GB model that would fill up the 80mm stick fully. Or, and unless the 3xpoint dies fully fill the area in the packages make them slightly smaller to support the 2260 form factor (after accounting for the odds and ends at the end of the stick the current design it looks like it's just too big to fit on the smaller size). Reply
  • CaedenV - Monday, April 24, 2017 - link

    Once again, I have to ask.... who on earth is this product for?
    So you have a cheap $300 laptop, which is going to have a terrible display, minimal RAM, and a small HDD or eMMC drive... are they expecting these users to spring for one of these drives to choke their CPU?

    Maybe a more mainstream $5-900 laptop where price is still ultra competitive. What sales metric does this add to which will promote sales over a cheaper device with seemingly the same specs? Either it will have a SSD onboard already and the performance difference will be un-noticed, or it will have a large HDD and the end-user is going to scratch their heads wondering why 2 seemingly identical computers have 4GB of RAM and 1TB HDD, but one costs $100 more.

    Ok, so maybe it is in the premium $1-2000 market. Intel says it isn't aiming at these devices, but they are Intel. Maybe they think a $1-2000 laptop is an 'affordable' mass-market device? Here you are talking about ultrabooks; super slim devices with SSDs... oh, and they only have 1 PCIe slot on board. Just add a 2nd one? Where are you going to put it? Going to add more weight? More thickness? A smaller battery? And even after you manage to cram the part in one of these laptops... what exactly is going to be the performance benefit? An extra half a second when coming out of sleep mode? Word opens in .5 sec instead of .8 sec? Yes, these drives are faster than SSDs... but we are way past the point of where software load times matter at all.

    So then what about workstation laptops. That is where these look like they will shine. A video editing laptop, or desktop replacement. And for those few brave souls using such a machine with a single HDD or SSD this seems like it would work well... except I don't know anyone like that. These are production machines, which means RAID1 in case of HDD failure. And this tech does not work with RAID (even though I don't see why not... seems like they could easily integrate this into the RAID controller). But maybe they could use the drive as a 3rd small stand-alone render drive... but that only works in linux, not windows. So, nope, this isn't going to work in this market either.

    And that brings us to the desktop market. For the same price/raid concerns this product really doesn't work for desktops either, but the Optate SSDs coming out later this year sound interesting... but here we still have a pretty major issue;
    SATA3 vs PCIe m.2 drives have an odd problem. On paper the m.2 drives benchmark amazingly well. And in production environments for rendering they also work really well. But for work applications and games people are reporting that there is little to no difference in performance. Intel is trying to make the claim that the issue is due to access time on the controllers, and that the extremely fast access time on Optane will finally get us past all that. But I don't think that is true. For work applications most of the wait time is either on the CPU or the network connection to the source material. The end-user storage is no longer the limiting factor in these scenarios. For games, much of the load time is in the GPU taking textures and game data and unpackaging them in the GPU's vRAM for use. The CPU and HDD/SSD are largely idle during this process. Even modern HDDs keep up pretty well with their SSD brethren on game load times. This leads me to believe that there is something else that is slowing down the whole process.

    And that single bottleneck in the whole thing is Intel. It is their CPUs that have stopped getting faster. It is their RAM management that rather sucks and works the same speed no matter what your RAM is clocked at. It is the whole x86 platform that is stagnant and inefficient which is the real issue here. It is time for Intel to stop focusing on its next die-shrink, and start working on a new modern efficient instruction set and architecture that can take advantage of all this new tech! Backwards compatibility is killing the computer market. Time to make a clean break on the hardware side for a new way of doing things. We can always add software compatibility in an emulation layer so we can still use our old OSs and tools. Its going to be a mess, but we are at a point where it needs to be done.
    Reply
  • Cliff34 - Monday, April 24, 2017 - link

    It seems to me that this product doesn't really make sense for your average consumer. Let's assume you don't need to upgrade your hardware to use Optane memory as cache, why not just spend the money to get a faster and a bigger SSD drive?

    If that's the case, wouldn't it limited to only a few specific case where someone really need the Optane speed?
    Reply
  • mkozakewich - Thursday, April 27, 2017 - link

    An extra 4 GB of DDR4 seems to be $30-$40, so getting 16 GB of swap drive for the same price might be a good way to go.
    I agree that using it for caching seems a little pointless.
    Reply
  • zodiacfml - Monday, April 24, 2017 - link

    Wow, strong at random perf where SSDs are weak. I guess this will be the drive for me. Next gen please. Reply
  • p2131471 - Monday, April 24, 2017 - link

    I wish you'd make interactive graphs for random reads. Or at least provide numbers in a table. Right now I can only approximate the exact values. Reply

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