Hi,
right, QUORUM means that data is written to all replicas but the coordinator waits for QUORUM responses before returning back to client. If a replica is out of sync due to network or internal issue than consistency is ensured through: - HintedHandoff (Automatically http://www.datastax.com/documentation/cassandra/2.0/cassandra/dml/dml_about_hh_c.html) - ReadRepair (Automatically http://www.datastax.com/documentation/cassandra/2.0/cassandra/dml/dmlClientRequestsRead.html) - nodetool repair (Manually http://www.datastax.com/documentation/cassandra/2.0/cassandra/operations/ops_repair_nodes_c.html) Regards Andi ________________________________ From: Flavien Charlon [[email protected]] Sent: 19 January 2015 22:50 To: [email protected] Subject: How do replica become out of sync Hi, When writing to Cassandra using CL = Quorum (or anything less than ALL), is it correct to say that Cassandra tries to write to all the replica, but only waits for Quorum? If so, what can cause some replica to become out of sync when they're all online? Thanks Flavien
