[jwr]

Have those mmap limitations really impacted you? And the corruption — I'm assuming that was with read/write mappings that you wrote to?

I'm asking, because we're getting great mileage out of mmap in Clojure, albeit for read-only mappings. And that's in a search engine :-) Using mmap for large data is great, because you avoid enlarging your heap and the garbage collector doesn't even have to care about your data.