Application to OS: Did you write that data out to disk? OS: Yes, I did. OS' inner voice: Nah, I didn't, but I'll do it soon, I think. OS to drive: Those writ

Application to OS: Did you write that data out to disk? OS: Yes, I did. OS' inner voice: Nah, I didn't, but I'll do it soon, I think. OS to drive: Those write commands, they're durable yet? Drive: Sure! Drive's inner voice: Nah, they're still in my RAM, but I'll probably write them out any time now.