Backing up your data should be a regular process on your cluster to ensure that you do not lose information in the event of a serious hardware or installation failure.
For detailed information on the restore processes and options, see Section 5.2.2, “Restore”.
It is a best practice to backup and restore all nodes together to minimize any inconsistencies in data. Couchbase is always per-item consistent, but does not guarantee total cluster consistency or in-order persistence.