Server security

What if the couchbase server crashes and I am using just one cluster with
a) one node only
b) multiple nodes.
How will the data be protected in that case ?

Hi @vishal00921, Couchbase natively supports high availability so that the data is always available. Users need to design the cluster for high availability. More information is available in the official documentation :

For one node clusters too, the data will be protected in cases of server crashes. Once the node is back up, the data will be recovered from on-disk snapshots.