Error: "Could not open Hibernate Session for transaction" when using Commvault to take backups of Virtual Machines

Products

• VMware Cloud Director

Issue/Introduction

• Random Virtual Machines backups are getting failed while using Commvault where the Virtual Machines (VM) reside inside VMware Cloud Director(VCD).
• You can find the below error messages in Commvault: 
  
  Could not open Hibernate Session for transaction; nested exception is org.hibernate.exception.GenericJDBCException: Cannot open connection
  at com.vmware.vcloud.common.db.Hibernate3TransactionManager.doBegin(Hibernate3TransactionManager.java:193)
  
  
• You will find the below error message in VCD tasks:
  
  - FATAL: no pg_hba.conf entry for host "##.##.##.##", user "vcloud", database "vcloud", SSL encryption

Environment

• VMware Cloud Director 10.6.1.1
• Commvault

Cause

The issue will be caused if the VCD cluster status is showing DEGRADED because of a standby cell which was unable to communicate with the rest of the VCD. There is an incorrect configuration within the pg_hba.conf file which blocks the communication to and from the standby cell. As a result any VM backup task coming to the affected standby cell gets into an errored state and the VM backup fails. 

Resolution

To resolve the issue unregister the affected standby cell. To unregister the affected cell you can follow the document: Unregister a Standby Cell in Your VMware Cloud Director Database High Availability Cluster and make the VCD VAMI HEALTHY again. 

For more details on DEGRADED status you can follow the kb: VAMI shows Cluster Health: Read Only Primary or Degraded state