Why did the CA Performance Management  Data Aggregator shut down and/or will not start

Data Aggregator down. Tried to restart without success.
 
Cannot start Data Aggregator 
 
Data Aggregator will not restart 
 
Data Aggregator is down and showing Synchronization Failure in DX NetOps Performance Management Performance Center web UI.

Data Aggregator down

Data Aggregator will not restart 

Data Repository Vertica database is down and not running. As a result the Data Aggregator dadaemon service shuts itself down to protect itself. It will not successfully restart until the database is restarted as well.

The Data Aggregator will shut down when it can no longer contact any Data Repository hosts.

The Data Aggregator will not start down if it can not contact any Data Repository hosts.

On the Data Aggregator, in the ${da.karaf.home}/shutdown.log you will see messages similar to the following:

WARN  | :DRHOSTNAME-01 | 2018-05-04 02:40:05,458 | shutdown | ase.heartbeat.DBStateManagerImpl  731 | ase.heartbeat.DBStateManagerImpl  731 | ommon.core.services.impl |       | DB state for host DRHOSTNAME-01 changing from OK to DOWN
ERROR | anager-thread-13 | 2018-05-04 02:40:05,468 | shutdown | ces.shutdown.ShutdownManagerImpl  131 | ces.shutdown.ShutdownManagerImpl  131 | ommon.core.services.impl |       | Shutting down the data aggregator.It was detected that no data repository nodes were contactable. The uncontactable hosts are:[DRHOSTNAME-01]
ERROR | anager-thread-14 | 2018-05-04 02:40:05,468 | shutdown | tTolerantDBConnectionManagerImpl  221 | tTolerantDBConnectionManagerImpl  221 | ommon.core.services.impl |       | No DB host name available.
INFO  | anager-thread-14 | 2018-05-04 02:40:05,469 | shutdown | tTolerantDBConnectionManagerImpl  376 | tTolerantDBConnectionManagerImpl  376 | ommon.core.services.impl |       | The primary host for database transactions is now set to null
ERROR | anager-thread-14 | 2018-05-04 02:40:05,469 | shutdown | tTolerantDBConnectionManagerImpl  179 | tTolerantDBConnectionManagerImpl  179 | ommon.core.services.impl |       | The primary data repository host 'DRHOSTNAME-01' is no longer available, and there are no available secondary hosts. Current Host Status: {DRHOSTNAME-01=DOWN}
 
You can get the location of da.karaf.home from the /etc/DA.cfg:

]$ grep 'da.karaf.home' /etc/DA.cfg
da.karaf.home=/opt/IMDataAggregator/apache-karaf-2.4.3

After starting the Data Repository, start the Data Aggregator:

service dadaemon start