Before your application goes into production, you will need to determine your cluster size. This includes:
Determine how many initial nodes will be required to support your user base,
Determine how much capacity you need for data storage and processing in terms of RAM, CPU, disk space, and network bandwidth.
Determine the level of performance availability you want.
For instance, if you want to provide high-availability for even a smaller dataset, you will need a minimum of three nodes for your cluster. For detailed information about determining cluster and resource sizing, see Couchbase Server Manual: Sizing Guidelines.