4 ms·

The replica count seems to be three - allowing quorum with a single lost host - and the repository goes read-only when quorum is lost.

• im_down_w_otp 11y ago
  That doesn't do anything to resolve consistency issues. The only time that quorum, pinned to primary replicas (i.e. disallowing sloppy failovers), helps you with consistency is when all reads and writes to those replicas are funneled through a serialized reader/writer. Then that serialized process can ensure "Read Your Own Writes" consistency using majority quorum (again, pinned to primary replicas). So they're either doing strongly coordinated writes to make sure replication changes are consistent (serializer, consensus, or chain), they're encoding other causal information in the data and have some method that deterministically picks which replica should dominate the others, or they're silently losing updates on conflicts. It would be cool to know what they're doing.
  • prirun 11y ago
    The article said "Writes are synchronously streamed to all three replicas and are only committed if at least two replicas confirm success."
    • im_down_w_otp 11y ago
      Somehow missed that. Thank you. So quorum + 2PC is what that sounds like to me. Suffice it to say, that's not a safe protocol without some other system guarantees in place.