Mark Williams thinks about the future of the PC memory landscape and how it could all change.
An instant-on PC. The idea for such a thing has been around for quite a while; it was at least a decade ago, maybe more, when I first heard of the concept, which was always bandied about when some new experimental types of memory had been invented that were non-volatile (I recall something about phase change and plastics. Yeah, crazy experimental!). This means the system could shut down and power off but everything in memory remained and was instantly available at boot, allowing the system to effectively pick up where it left off without reloading everything from a mass storage device again. None of them appear to have made it out of the research labs though, until now.
While we’re still not anywhere near the instant-on dream just yet, Intel and Micron are beginning to roll out a completely new type of memory (the first since about 1966) that will redefine the memory hierarchy in computer systems.
Called 3D XPoint (pronounced ‘cross point’) this new type of memory behaves somewhere between DRAM (as in DDR4 etc) and NAND (as in SSDs). This is because 3D XPoint is almost as responsive as DRAM with low latencies, but is non-volatile like NAND – and has capacities near NAND too.
This has led Intel to release 3D XPoint products under its new Optane brand name that are focused on caching and acting as an intermediary in the memory/storage hierarchy between your SSD/HDD and RAM to speed up read/write characteristics of those mass storage devices. In essence treating it like they did SSDs to HDDs when those were just coming to market back in the day, and weren’t yet capacious enough to be used as a storage device all by themselves.
3D Xpoint and Optane products may still yet get to SSD capacities, and if they do we’ll see another leap forward in mass storage bandwidth and latencies, just as SSDs have done over HDDs over the past decade. It is an order of magnitude faster.
Intel has released a server-only Optane product that’s much like a PCIe card-based NVMe SSD, but powered by 3D XPoint. It’s already blowing away server metrics and benchmarks at low queue depths (where everyone, even servers, mostly operate at), something NAND isn’t as good at as it needs to exploit the parallelism of a high queue depth to reach the peaks quoted in spec sheets.
Intel is even exploring putting 3D XPoint onto memory DIMMs for servers to use directly via their memory slots, enlarging memory capacities and adding the safety net of a non-volatile memory sub system.
It will be a long time before Intel and Micron fully ramp up 3D XPoint production, but as they do it will be interesting to see how the PC landscape adapts to this new memory/storage tier. Will it replace SSDs or DRAM? Or simply become yet another tier of memory/storage and will become as common place in systems as DRAM and SSDs/HDDs? Only time will tell. I can’t wait!
We hope to have a review of one of these new consumer-level Optane products soon. Stay tuned.
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