Other Approaches (cont’d)
Read-one replica, write-all-available replicas
- Requires careful management of failures and recoveries
E.g., Virtual partition algorithm
- Each node knows the nodes it can communicate with, called its view
- Transaction T can execute if its home node has a view including a quorum of T’s readset and writeset (i.e. the data it can read or write)
- If a node fails or recovers, run a view formation protocol (much like an election protocol)
- For each data item with a read quorum, read the latest version and update the others with smaller version #.