Cluster Manager consists of two processes. The first, the babysitter, is responsible for maintaining a variety of Couchbase Server-processes, which indeed include the second Cluster Manager process, ns-server.
The babysitter starts and monitors all of these processes, logging their output to the file babysitter.log
The processes for which the babysitter is responsible are:
1) ns-server: Manages the node’s participation in the cluster, as described in ns-server, below.
2) kv engine: Runs as part of the Data Service, which must be installed on at least one cluster-node. Provides access to Data.
3) services: One or more Couchbase Services that optionally run on the node.
4) xdcr: The program for handling Cross Data-Center Replication (XDCR). This is installed with the Data Service, but runs as an independent OS-level process, separate from the Cluster Manager itself.
5) view engine: The program for handling Views. This is installed with the Data Service, but runs as an independent OS-level process, separate from the Cluster Manager itself.
Check more about Cluster Manager Architecture