Hybrid storage solutions are nothing new, but they typically combine solid-state and mechanical storage. A team of Japanese researchers has now developed a hybrid SSD design that relies on two flavors of solid-state storage: NAND and ReRAM. Unlike DRAM, memristor-based ReRAM is non-volatile, allowing it to serve as cache in a drive otherwise made up of traditional NAND.
TechOn has more details on the “SSD architecture,” which has been modeled on a 256GB drive with 1GB of ReRAM cache. The ReRAM would be used several ways. It would cache incoming writes and push them to the NAND only when there was a full page of data to write. Frequently accessed data would be stored in ReRAM, which could also serve as spare area for the controller.
The group anticipates its hypothetical hybrid would offer better performance, lower power consumption, and a longer lifespan than typical SSDs. Actual drives based on the approach might not be far off, either. HP, which is producing ReRAM in cooperation with Hynix, expects the first chips to be available next year. Samsung is working on memristor tech, too.
If ReRAM chips offer better performance and longevity than NAND, I can see hybrid implementations becoming popular. ReRAM is likely to be expensive when it comes out, but you wouldn’t need much of it to serve as a cache. The storage folks also have time to hone their caching algorithms with implementations that combine solid-state and mechanical storage, though those algorithms would certainly need tweaking for purely solid-state hybrids.