I don't know, that's 230k saves a second .. that's no joke no matter what platform you're using. I am not super familiar with sharding in MongoDB (haven't needed to go there yet) but seems like 230k writes/second would stress pretty much anything, and Mongo only added that functionality fairly recently.
Personally I am not at all worried about having to deal with 230k writes/second, though. If one of my apps ever gets that large, I will expect my far-smarter-than-me head of DB ops to deal with it, then send me an email telling me all about how he'd solved the problem, which I will read with great interest from on board my gold-plated yacht.
No so fast with the yacht, he didn't say they're doing 230k saves/sec. That'd be the case if Warhamemr Online saved statuses for 7M concurrent users every 30 seconds. The basho guy said 7M daily users, not 7M concurrent ones.
Personally I am not at all worried about having to deal with 230k writes/second, though. If one of my apps ever gets that large, I will expect my far-smarter-than-me head of DB ops to deal with it, then send me an email telling me all about how he'd solved the problem, which I will read with great interest from on board my gold-plated yacht.