Coordinator Recovery
If the coordinator fails and later recovers, it must know the decision. It must therefore log
- the fact that it began T’s 2PC protocol, including the list of participants, and
- Commit or Abort, before sending Commit or Abort to any participant (so it knows whether to commit or abort after it recovers).
If the coordinator fails and recovers, it resends the decision to participants from whom it doesn’t remember getting Done
- If the participant forgot the transaction, it replies Done
- The coordinator should therefore log Done after it has received them all.