[wmf]

Diablo Memory1 used flash DIMMs with DRAM DIMMs as cache. When we tried it, it worked OK for some workloads and poorly for others, but it was also buggy and then the company went out of business. So a large part of "pans out" is simply a production-quality implementation that you can buy.

Note that Optane DIMMs have been delayed by around two years at this point and we still don't know what they will cost.