The Intel Optane Memory (SSD) Preview: 32GB of Kaby Lake Cachingby Billy Tallis on April 24, 2017 12:00 PM EST
- Posted in
- PCIe SSD
- SSD Caching
- 3D XPoint
- Optane Memory
Last week, we took a look at Intel's first product based on their 3D XPoint non-volatile memory technology: the Optane SSD DC P4800X, a record-breaking flagship enterprise SSD. Today Intel launches the first consumer product under the Optane brand: the Intel Optane Memory, a far smaller device with a price that is 20 times cheaper. Despite having "Memory" in its name, this consumer Optane Memory product is not a NVDIMM nor is it in any other way a replacement for DRAM (those products will be coming to the enterprise market next year, even though the obvious name is now taken). Optane Memory also not a suitable replacement for mainstream flash-based SSDs, because Optane Memory is only available in 16GB and 32GB capacities. Instead, Optane Memory is Intel's latest attempt at an old idea that is great in theory but has struggled to catch on in practice: SSD caching.
Optane is Intel's brand name for products based on the 3D XPoint memory technology they co-developed with Micron. 3D XPoint is a new class of non-volatile memory that is not a variant of flash memory, the current mainstream technology for solid state drives. NAND flash memory—be it older planar NAND or newer 3D NAND flash—has fundamental limits to performance and write endurance, and many of the problems get worse as flash is shrunk to higher densities. 3D XPoint memory takes a radically different approach to non-volatile storage, and it makes different tradeoffs between density, performance, endurance and cost. Intel's initial announcement of 3D XPoint memory technology in 2015 came with general order of magnitude comparisons against existing memory technologies (DRAM and flash). Compared to NAND flash, 3D XPoint is supposed to be on the order of 1000x faster with 1000x higher write endurance. Compared to DRAM, 3D XPoint memory is supposed to be about 10x denser, which generally implies it'll be cheaper per GB by about the same amount. Those comparisons were about the raw memory itself and not about the performance of an entire SSD, and they were also projections based on memory that was still more than a year from hitting the market.
3D XPoint memory is not intended or expected to be a complete replacement for flash memory or DRAM in the foreseeable future. It offers substantially lower latency than flash memory but at a much higher price per GB. It still has finite endurance that makes it unsuitable as a drop-in replacement for DRAM without some form of wear-leveling. The natural role for 3D XPoint technology seems to be as a new tier in the memory hierarchy, slotting in between the smaller but faster DRAM and the larger but slower NAND flash. The Optane products released this month are using the first-generation 3D XPoint memory, along with first-generation controllers. Future generations should be able to offer substantial improvements to performance, endurance and capacity, but it's too soon to tell how those characteristics will scale.
The Intel Optane Memory is a M.2 NVMe SSD using 3D XPoint memory instead of NAND flash memory. 3D XPoint allows the Optane Memory to deliver far higher throughput than any flash SSD of equivalent capacity, and lower read latency than a NAND flash SSD of any capacity. The Optane Memory is intended both for OEMs to integrate into new systems and as an aftermarket upgrade for "Optane Memory ready" systems: those that meet the system requirements for Intel's new Optane caching software and have motherboard firmware support for booting from a cached volume. However, the Optane Memory can also be treated as a small and fast NVMe SSD, because all of the work to enable its caching role is performed in software or by the PCH on the motherboard. 32GB is even (barely) enough to be used as a Windows boot drive, though doing so would not be useful for most consumers.
Intel Optane Memory uses a PCIe 3.0 x2 link, while most M.2 PCIe SSDs use the full 4 lanes the connector is capable of. The two-lane link allows the Optane Memory to use the same B and M connector key positions that are used by M.2 SATA SSDs, so there's no immediate visual giveaway that Optane Memory requires PCIe connectivity from the M.2 socket. The Optane Memory is a standard 22x80mm single-sided card but the components don't come close to using the full length. The controller chip is far smaller than a typical NVMe SSD controller, and the Optane Memory includes just one or two single-die packages of 3D XPoint memory. The Optane Memory module has labels on the front and back that contain a copper foil heatspreader layer, positioned to cool the memory rather than the controller. There is no DRAM visible on the drive.
|Intel Optane Memory Specifications|
|Capacity||16 GB||32 GB|
|Form Factor||M.2 2280 B+M key|
|Interface||PCIe 3.0 x2|
|Memory||128Gb 20nm Intel 3D XPoint|
|Sequential Read||900 MB/s||1350 MB/s|
|Sequential Write||145 MB/s||290 MB/s|
|Random Read||190k IOPS||240k IOPS|
|Random Write||35k IOPS||65k IOPS|
|Read Latency||7µs||9 µs|
|Write Latency||18µs||30 µs|
|Active Power||3.5 W||3.5 W|
|Idle Power||1 W||1 W|
|Endurance||182.5 TB||182.5 TB|
The performance specifications of Intel Optane Memory have been revised slightly since the announcement last month, with Intel now providing separate performance specs for the two capacities. Given the PCIe x2 link it's no surprise to see that sequential read speeds are substantially lower than we see from other NVMe SSDs, with 900 MB/s for the 16GB model and 1350 MB/s for the 32GB model. Sequential writes of 145 MB/s and 290 MB/s are far slower than consumer SSDs are usually willing to advertise, but are typical of the actual sustained sequential write speed of a good TLC NAND SSD. Random read throughput of 190k and 240k IOPS is in the ballpark for other NVMe SSDs. Random write throughput of 35k and 65k IOPS are also below the peak speeds advertised my most consumer SSDs, but on par with mainstream TLC and MLC SSDs respectively for actual performance at low queue depths.
Really it's the latency specifications where Optane Memory shines: the read latency of 7µs and 9µs for the 16GB and 32GB respectively are slightly better than even the enterprise Optane SSD DC P4800x, while write latency of 18µs and 30µs are just 2-3 times slower. The read latencies are completely untouchable for flash-based SSDs, but the write latencies can be matched by other NVMe controllers, but only because they cache write operations instead of performing them immediately.
The power consumption and endurance specifications don't look as impressive. 3.5W active power is lower than many M.2 PCIe SSDs and low enough that thermal throttling is unlikely to be a problem. The 1W idle power is unappealing, if not a bit problematic. Many M.2 NVMe SSDs will idle at 1W or more if the system is not using PCIe Active State Power Management and NVMe Power States. The Optane Memory doesn't even support the latter and will apparently draw the full 1W even in a well-tuned laptop. Since these power consumption numbers are typically going to be in addition to the power consumption of a mechanical hard drive, an Optane caching configuration is not going to offer decent power efficiency.
Meanwhile write endurance is rated at the same 100GB/day or 182.5 TB total for both capacities. Even though a stress test could burn through all of that in a week or two, 100GB/day is usually plenty for ordinary consumer use. However, a cache drive will likely experience a higher than normal write load as data and applications will tend to get evicted from the cache only to be pulled back in the next time they are loaded. More importantly, Intel promised that 3D XPoint would have on the order of 1000x the endurance of NAND flash, which should put these drives beyond the write endurance of any other consumer SSDs even after accounting for their small capacity.
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name99 - Tuesday, April 25, 2017 - linkWhy 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.
emn13 - Tuesday, April 25, 2017 - linkIntel 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.
ddriver - Tuesday, April 25, 2017 - linkIIRC they have explicitly denied xpoint being PCM. But then again, who would ever trust a corporate entity, and why?
Cellar - Tuesday, April 25, 2017 - linkImplying 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*
name99 - Tuesday, April 25, 2017 - linkBe 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.
Reflex - Tuesday, April 25, 2017 - linkMeanwhile 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.
ddriver - Tuesday, April 25, 2017 - linkYeah, 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.
eddman - Tuesday, April 25, 2017 - linkThis 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"
ddriver - Tuesday, April 25, 2017 - linkExcept 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.
eddman - Tuesday, April 25, 2017 - linkJust 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.