Debian supports it.

I've had it installed on a server of mine and running for about six months now.  No issues, really.

Is there a stable Linux distro using btrfs?
Is it correct to ask "how do you say 'tower' in Spanish?" or should we actually ask "what's the Spanish word for 'tower'?" Some people say that if I ask "how do you say..." the answer would be softly, loudly etc., as if how was functioning as an adverb of manner and that was its only function. So, the correct question would be "what's the Spanish word for..." 

What do you think? is there any grammar rule that could help me understand the difference between these two questions?
