The Cluster Observer stores its information in memory, so when the Leader loses its leadership, the collected reports of the Cluster Observer and its decisions log are lost.
Interacting with the Cluster Observer
You can interact with the Cluster Observer using the following REST API calls:
Setting false will suspend the Cluster Observer operation for the current Leader term.
Fetch the log of the recent decisions made by the cluster observer.
Fetch the latest reports of the Cluster Observer
Let us assume a five node cluster, with servers A, B, C, D, E.
We create a database with a replication factor of 3 and define an ETL task.
The newly created database will be distributed automatically to three of the cluster nodes.
Let's assume it is distributed to B, C and E (So the database group is [B,C,E]),
and the cluster decides that node C is the responsible for performing the ETL task.
If node C goes offline or is not reachable, the Observer will notice it and relocate the database from node C to another available node.
Meanwhile the ETL task will failover to be performed by another available node from the Database Group.