While running Deduplicated Backups to a MediaAgent and Disk Library using CIFs, it will reference existing Blocks written to the Library, and if the reference exist it will increment the references in the DDB (achieving space saving)
However depending on the type of Data Verification and Aux Copy that is ran, this operation is reading from the Source Library (CIFS in this case) and will encounter Process CHUNK errors under the following condition:
- Data Block is missing
- Data Block is corruptted
- Intermittent connection
If this is due to Corruption or Missing Blocks, a Full DDB Verification is recommended so the impacted blocks are marked as bad and won't be reference again during new Backup
However if this is an intermittent connection issues with CIF shares, it is recommended to review the OS logs to identify any possible connection errors from SMB layer. If there are no specific errors it would be best to check from Storage Layer and Network layer to see if there are TCP reset or packet drop when under load (as these are the general pain points encountered).
Likewise from a Commvault perspective you can review AuxCopy.log/CVJobReplicatorsODS.log (on Source MediaAgent) for Aux Copy and DataVerf.log for Data Verification, which will show more meaningful error logging to narrow your investigation