"Small note on the mmap thing; a lot of people consider the mmap based storage engine a big issue (I tend to agree)." This. Aside from general reliability iss

"Small note on the mmap thing; a lot of people consider the mmap based storage engine a big issue (I tend to agree)." This. Aside from general reliability issues I've had in the past, which are definitely fixable and might be now, this design decision is the thing that will cripple, and continue to cripple the db. The idea that some how the kernel is going to better at managing a db's memory is ridiculous. Kernel paging was designed for a completely different use case, it's not optimized to manage the memory of a database. The idea that somehow this line of reasoning: "oh hey guys, those Linux kernel hackers are smart and they can do it way better then use so let's just use their memory management system" was ok in the mind of the MongoDB creators really puts me off. It doesn't matter how many geniuses work on kernel memory management when they are solving a completely different problem then you need to solve, all memory management schemes aren't equal. When providing a db you need full control to be able to probably tune memory management to fit your needs, there is no magical fix for this.