We are working with EMC on the issue. The only thing we have been able to find is an EMC document for ECS and Commvault config with the following information regarding the additional settings tab.
Description: Used to set the size of the chunks to upload for the files in page mode.
Default value: 8192
Use: This parameter sets the chunk size (page mode) of files to upload to ECS when using
Note: This parameter sets the deduplication chunk size. Caution should be taken when modifying
this value because it has the potential to cause large amounts of un-reclaimable garbage in ECS.
I have not been able to find and docs on this additional setting. Our EMC reps know who wrote this
document and they are going to reach out to that person to see if they have more info on the issue.