Hi,
The growth rate specifies the average daily change in volume size (of total volume size).
You can use the "Volume Growth" report to tell you which volumes on all of your storage systems are full or are projected to be full soon.
Yes, the negative values indicate that some space has been reclaimed from the volume.
Please use this section of the community for your questions related to OnCommand Management Software.
https://communities.netapp.com/community/products_and_solutions/storage_management_software
Regards,
Pavan