Couchbase Server nodes can be in a number of different states depending on their current activity and availability. The displayed states are:
Host is up, replicating data between nodes and servicing requests from clients.
Host is down, not replicating data between nodes and not servicing requests from clients.
Host is up and currently filling RAM with data, but is not servicing requests from clients. Client access will be supported once the RAM has been pre-filled with information.
You can monitor the current server status using both the Manage: Server Nodes and Monitor: Server Nodes screens within the Web Console.