I have found that for one of the nodes in a DR ( 3 server cluster ) , automatic backup is not happening.
If one node is down in a 3 node vertica cluster, the backup will work but the down node will not be included.
Release : 3.7
Component : IM Reporting / Admin / Configuration
Using admintools, select option 5
Restart vertica on node.
Once the node has recovered, manually run a backup.