Last week, Intel officially launched their first Optane product, the SSD DC P4800X enterprise drive. This week, 3D XPoint memory comes to the client and consumer market in the form of the Intel Optane Memory product, a low-capacity M.2 NVMe SSD intended for use as a cache drive for systems using a mechanical hard drive for primary storage.

The Intel Optane Memory SSD uses one or two single-die packages of 3D XPoint non-volatile memory to provide capacities of 16GB or 32GB. The controller gets away with a much smaller package than most SSDs (especially PCIe SSD) since it only supports two PCIe 3.0 lanes and does not have an external DRAM interface. Because only two PCIe lanes are used by the drive, it is keyed to support M.2 type B and M slots. This keying is usually used for M.2 SATA SSDs while M.2 PCIe SSDs typically use only the M key position to support four PCIe lanes. The Optane Memory SSD will not function in a M.2 slot that provides only SATA connectivity. Contrary to some early leaks, the Optane Memory SSD uses the M.2 2280 card size instead of one of the shorter lengths. This makes for one of the least-crowded M.2 PCBs on the market even with all of the components on the top side.

The very low capacity of the Optane Memory drives limits their usability as traditional SSDs. Intel intends for the drive to be used with the caching capabilities of their Rapid Storage Technology drivers. Intel first introduced SSD caching with their Smart Response Technology in 2011. The basics of Optane Memory caching are mostly the same, but under the hood Intel has tweaked the caching algorithms to better suit 3D XPoint memory's performance and flexibility advantages over flash memory. Optane Memory caching is currently only supported on Windows 10 64-bit and only for the boot volume. Booting from a cached volume requires that the chipset's storage controller be in RAID mode rather than AHCI mode so that the cache drive will not be accessible as a standard NVMe drive and is instead remapped to only be accessible to Intel's drivers through the storage controller. This NVMe remapping feature was first added to the Skylake-generation 100-series chipsets, but boot firmware support will only be found on Kaby Lake-generation 200-series motherboards and Intel's drivers are expected to only permit Optane Memory caching with Kaby Lake processors.

Intel Optane Memory Specifications
Capacity 16 GB 32 GB
Form Factor M.2 2280 single-sided
Interface PCIe 3.0 x2 NVMe
Controller Intel unnamed
Memory 128Gb 20nm Intel 3D XPoint
Typical Read Latency 6 µs
Typical Write Latency 16 µs
Random Read (4 KB, QD4) 300k
Random Write (4 KB, QD4) 70k
Sequential Read (QD4) 1200 MB/s
Sequential Write (QD4) 280 MB/s
Endurance 100 GB/day
Power Consumption 3.5 W (active), 0.9-1.2 W (idle)
MSRP $44 $77
Release Date April 24

Intel has published some specifications for the Optane Memory drive's performance on its own. The performance specifications are the same for both capacities, suggesting that the controller has only a single channel interface to the 3D XPoint memory. The read performance is extremely good given the limitation of only one or two memory devices for the controller to work with, but the write throughput is quite limited. Read and write latency are very good thanks to the inherent performance advantage of 3D XPoint memory over flash. Endurance is rated at just 100GB of writes per day, for both 16GB and 32GB models. While this does correspond to 3-6 DWPD and is far higher than consumer-grade flash based SSDs, 3D XPoint memory was supposed to have vastly higher write endurance than flash and neither of the Optane products announced so far is specified for game-changing endurance. Power consumption is rated at 3.5W during active use, so heat shouldn't be a problem, but the idle power of 0.9-1.2W is a bit high for laptop use, especially given that there will also be a hard drive drawing power.

Intel's vision is for Optane Memory-equipped systems to offer a compelling performance advantage over hard drive-only systems for a price well below an all-flash configuration of equal capacity. The 16GB Optane Memory drive will retail for $44 while the 32GB version will be $77. As flash memory has declined in price over the years, it has gotten much easier to purchase SSDs that are large enough for ordinary use: 256GB-class SSDs start at around the same price as the 32GB Optane Memory drive, and 512GB-class drives are about the same as the combination of a 2TB hard drive and the 32GB Optane Memory. The Optane Memory products are squeezing into a relatively small niche for limited budgets that require a lot of storage and want the benefit of solid state performance without paying the full price of a boot SSD. Intel notes that Optane Memory caching can be used in front of hybrid drives and SATA SSDs, but the performance benefit will be smaller and these configurations are not expected to be common or cost effective.

The Optane Memory SSDs are now available for pre-order and are scheduled to ship on April 24. Pre-built systems equipped with Optane Memory should be available around the same time. Enthusiasts with large budgets will want to wait until later this year for Optane SSDs with sufficient capacity to use as primary storage. True DIMM-based 3D XPoint memory products are on the roadmap for next year.

Source: Intel

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  • saratoga4 - Monday, March 27, 2017 - link

    Should be similar to NAND.
  • bcronce - Tuesday, March 28, 2017 - link

    Not even close. Q4 random read for NAND is about 10% of Seq. Random write has high throughput by masking with those 1GiB+ caches. Samsung 960 Pro M.2 has an average random read latency of about 150us, which is about 25x worse. Expect the latencies to get further worse as SSDs get higher densities.

    I expect 3D XPoint to get lower latencies as the controllers improve, assuming we're not already against PCIe's limit.
  • andychow - Sunday, April 2, 2017 - link

    But he is correct that random read and write for this products are the same as their sequential numbers. Just multiply the i/o by the block size for the random, and bingo, you have the sequential speeds.
  • unrulycow - Monday, March 27, 2017 - link

    It's hard to see where the market for this is. It only makes sense if your primary workload is small enough to fit in the cache, but you need more storage than fits into a reasonably priced SSD. Most use cases will be significantly faster with a SSD.
  • Gothmoth - Monday, March 27, 2017 - link

    im an not impressed.... those who want best perfromance will buy a fast M.2 SSD not this stuff.
  • YazX_ - Monday, March 27, 2017 - link

    useless, the price for 32GB is same as 512GB SSD, so better to use SSD instead of this piece of waste of time and money.
  • cekim - Monday, March 27, 2017 - link

    Better to get 32G or more of DDR.

    They seem to be off by an order of magnitude in their talk of making vast memory images with this caching mechanism worth-while. Surprisingly enough (not at all), caches work. Applications, compilers and coders have long ago found ways of dealing with tiered latency and throughput. So, if you are going to make a difference, disks the size of very, very small memory foot-prints aren't it.

    Come talk to me when there are capital T's in the size...
  • MrSpadge - Monday, March 27, 2017 - link

    "32GB is same as 512GB SSD"
    You get decent 512 GB SSDs for 77$, when the cheapest one (MX300) costs 140€ here? Amazing, you should open up a business.
  • nagi603 - Monday, March 27, 2017 - link

    ...damn, why 2280 only? Seriously, use the damn size advantage!
  • DanNeely - Monday, March 27, 2017 - link

    Probably cost reasons and logistics. Current prices make a module big enough to be a system drive prohibitively expensive in an minimum enthusiast class size (~$275 for 128gb), so there's no point behind a larger module. From the other direction the pictured one is big enough that assuming it's the 32GB size that 2260 size might not fit the 2nd optane storage chip; and as a very niche device running up costs with separate 16/32gb PCBs isn't a good idea.

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