3 ms·

Clearly in 1b a node cannot be up if it is failed--we are talking about the case nodes remaining "up" when they are disconnected. (There aren't many interesting

Clearly in 1b a node cannot be up if it is failed--we are talking about the case nodes remaining "up" when they are disconnected. (There aren't many interesting tradeoffs available for completely failed nodes!) Also, the post does define consistency: "Normally, the system is consistent (a read sees all previously completed writes)."

notacoward 12y ago
Yes, clearly a node cannot be up if it's failed, and yet you refer to "perfect" consistency and "all" nodes. That's the inconsistency (heh) that you need to fix. Speaking of consistency, I stand corrected that you did define it . . . incorrectly. That's a definition of consistency, but it's not the operative one when it comes to CAP. Gilbert and Lynch specifically refer to atomic or linearizable consistency in 2.1, and that's a stronger requirement than yours as it also precludes reading still-in-progress writes. The definition of consistency is central to the proof, so if you want to put down others for not understanding CAP it helps to get it right yourself.