When running the nuodbmgr command “SHOW DOMAIN SUMMARY” you may get a message indicating a TE or SM engine process is in an UNREACHABLE state. This message indicates that the process is in the DSM (Durable State Machine) but not seen in the transient running state.
There are several ways this might occur.
1) Agent process exited. A broker only knows the process is running if the agent tells it.
2) Process died/left but DSM did not get cleaned up. Typically a restart of the agent will fix this.
3) Network communications problems between host A, Broker can't talk to the agent or processes on other host.
1) Check if the process is running or not.
2) Try to restart the nuoagent process on that host.
3) Run 'nuosql 'select * from system.nodes;' to make sure all nodes communicate with each other. In addition, you can also run the Linux command ‘ping’ from one node to the other.