My company purchased a new DD6900. We are using the Commvault backup app. ver 11.28. Our media agent is a windows server 2019. We are mounting the data domain volume using boostfs over the network. The backups ran without problem. However when we began a tape aux copy, it alerted that it could not read some of the data. I verified this by trying a restore. it appears some of the data is either corrupt or Commvault is blocked from reading it. 
If anyone is using a similar setup, id appreciate your input. I have support tickets open with Dell and Commvault and neither can point to anything that may cause data corruption or block a read somehow.