In a distributed system with data replication only two of the following properties can be guaranteed at the same time:

• Consistency: the nodes will have the same copies of a replicated data item visible for various transactions

• Availability: each read or write request for a data item will either be processed successfully or will receive a message that the operation cannot be completed.

• Partition Tolerance: the system can continue to operate if the network connecting the nodes has a fault that results in two or more partitions, where the nodes in each partition can only communicate among each other