To help deal with DRAM's volatile nature, some servers come equipped with NVDIMMs. They come in a few types, but the most common type are simply special memory modules that have DRAM and NAND flash on the same package. In the event of a power failure, the modules back up their contents onto the flash memory. The downside of using NVDIMMs—besides their higher cost—is that they limit your total memory capacity. That restriction just got relaxed quite a bit today, though. Micron has announced 32GB NVDIMMs.
The new modules will initially be available in speeds up to 2933 MT/s, which is already quite fast for registered ECC memory. Digging into Micron's datasheet, the company also lists 3200 MT/s modules, although there's no telling when they'll be available. 32GB per module is still quite a bit less memory than is available using more traditional memory modules, but obviously the higher-capacity competition lacks the non-volatile "near storage."
It's possible that we'll eventually find a non-volatile storage medium that is fast enough to replace DRAM. Intel and Micron's own 3D Xpoint is just one contender in that space. In that event, we may not have separate RAM and storage, and instead, we'll simply use that new medium for all of our memory needs. Until that time comes, though, we still need DRAM. Micron is showing the new memory modules operating inside a Dell PowerEdge 14G server at the SC17 conference right now. However, they still show as "sampling" in the company's catalog, so you'll probably have to wait a bit to get your hands on a system so equipped.