Do these really have RAM-like performance or is Intel calling them DIMMs as a marketing ploy?
I still remember when Optane was first announced Intel hyped it as a replacement for RAM. When it was finally available it turned out to be about 1,000x slower than RAM and barely faster than other SSD. So much for RAM replacement...
Barely faster than NVMe SSDs when fully saturated. At low queue depths and in mixed workloads (especially when overwriting data) Optane absolutely destroys the competition. This is a database dream drive. Only problem is the low capacities right now.
> Barely faster than NVMe SSDs when fully saturated.
The Optane products released thus far are all literally NVMe SSDs, which is why their best-case latency isn't much better than that of flash-based NVMe SSDs. They still have PCIe and NVMe protocol overhead to deal with, which the 3D XPoint DIMMs won't have.
The unimpressive peak throughput of the current Optane SSDs is largely a consequence of the Optane SSD controller having a fairly low channel count. A single 3D XPoint DIMM will probably have substantially higher throughput than a current Optane SSD.
I also wonder if the current products are bottlenecked by the controller and whether DIMMs will see vastly superior performance. Guess we'll have to wait and see.
> I also wonder if the current products are bottlenecked by the controller
There's no question that they are. NVMe drive prototypes that use DRAM as their backing memory instead of flash or some other persistent memory have about the same overall latency as Optane SSDs.
With NVMe, the storage industry is in a much better position to take advantage of 3D XPoint than if we were all still using SATA or SAS, but it's still on a peripheral bus not a memory bus.
NAND already has reached it's peak. I don't see why people are so disappointed that the first generation of a rushed product is competitive with todays high end NAND SSDs.
There was a time that Intel was telling us that this was so much better than NAND that it represented an entirely new tier in the storage hierarchy, sitting between DRAM and SSDs.
"DIMM" stands for dual in-line memory module, it is not about speed. It means that there are pins on both sides of the module with different signals (as opposed to SIMM).
Technically you are correct (the best kind of correct). But on a standard PC motherboard/configuration, DIMM slots are used exclusively for RAM which is much faster than ROM/storage. 3dxpoint was specifically marketed as being almost like a RAM/ROM hybrid in application. You could have 32GB RAM for regular computing plus 512GB of optane in the remaining DIMM slots and it would be like having swap space with very little speed penalty.
So GP is right to be concerned about speed for these form factors. If it's not faster than an NVMe drive them it's not worth the price.
NVDIMM-N's have more flash than RAM simply for wear leveling concerns. Micron's 32GB NVDIMM-N has 32GB of RAM and 64GB of flash, but the capacity of the NVDIMM-N is equal to the amount of RAM.
And considering Intel is positioning these as an exclusive enterprise product, RAM is probably going to be competitively priced, even in terms of storage space.
I still remember when Optane was first announced Intel hyped it as a replacement for RAM. When it was finally available it turned out to be about 1,000x slower than RAM and barely faster than other SSD. So much for RAM replacement...