Couchbase - what happens if a node dies after writing data to disk but before it gets replicated

Question

Here is the scenario.

I have two nodes under my couchbase server, Node A and B.I have replication on, so B will act as the node where replicated data of A should go.

Lets say that I try adding a new record and it happen to get saved at node A. Node A saves this data on RAM and on its disk successfully but UNFORTUNATELY, it crashes even before this data could get replicated to Node B

If I have configured automatic failover, Then all requests for Node A data will now go to Node B.

My question is Will I be able to get this new data which could not get replicated to node B but was successfully written over Node A's Disk? considering that Node A is down and all i have is Node B to communicate with

If yes, Please explain how. if no, Is there any official couchbase doc mentioning this behavior.

I tried looking for an answer in the official document and mostly it look like that answer is no, But thought of discussing this here before concluding that its data loss for sure.

Thanks in advance

Answer 1

In the scenario you described, yes the data will not be available, assuming you didn't check that the data had been successfully replicated. However note that replication will typically complete before perisistance, as the network is typically faster than disk.

Couchbase provides an observe API which allows you to verify that a particular mutation has been replicated and/or persisted. See Monitoring data using observe in the Couchbase developer guide.