> None of how MongoDB works is a secret.
Maybe not now, but this hasn't always been the case. The fact that they had (have?) a global write lock was completely buried on the doc site for ages. Benchmarks were waved in front of developer's faces to distract them from the "drivers don't actually write data, they just blast it out in every direction and hope it lands somewhere good" BS.
I don't use Mongo anymore, and I think a lot of it has not to do with the database itself, but with the way 10gen used their marketing machine in a dishonest way. They incurred a lot of trust-debt, and now have a serious amount of work to do to pay it back.