The Buckets section provides two graphs showing the Operations per second and Disk fetches per second.

Figure 6.3. Web Console — Cluster Overview — Buckets

The Operations per second provides information on the level of activity on the cluster in terms of storing or retrieving objects from the data store.

The Disk fetches per second indicates how frequently Couchbase is having to go to disk to retrieve information instead of using the information stored in RAM.