VOX

If the failed backup job log has VSS writer related messages, please reboot the Exchange server and run backups. Else please provide the error details in the Exchange backup job log.

Please check whether backup sets are getting expired and deleted as per the retention setting you have configured (10 weeks) from the Backup Exec Interface. As it is Deduplication storage, there might be many old files which are still used as the ref...

As its a vSphere limitation, Backup Exec currently not supporting the backup of VVols through SAN transport mode.Please check below links for more information.https://docs.vmware.com/en/VMware-vSphere/6.5/com.vmware.vsphere.storage.doc/GUID-03BDCF01-...