Our latest MySQL white paper is Improving Percona Server performance with Flashcache on the Virident tachIOn Drive. (Virident funded the research, but as always, we wrote the report ourselves.)
The conclusion is that Flashcache can be good for read-heavy workloads, but more research is needed to understand its performance characteristics on write-heavy workloads. We explain the details of exactly how good and under what circumstances. We also developed some guidelines for sizing and pricing, to serve as advice for those interested in deploying Flashcache as a way of getting some of the benefit of flash without all of the cost, or the size limitations.
