For this type of reporting you may want to look into some of the OnCommand products. OnCommand Insight (OCI) has a powerful reporting suite called OnCommand Insight Data Warehouse, which utilizes an IBM Cognos reporting engine to allow creation of complex reports that can be scheduled. I would recommend having a look at OCI to see if it is something you are interested in.
Re: How to find Volume data change rate in Cluster dataontap for last 2 weeks
I don't believe that particular metric is available pre-calculated in OnCommand Unified Manager or System Manager. However, if you wanted to throw together a custom solution you could have a look at the "NetApp Harvest" data collector, which can be found in the ToolChest section of the support site. You would need to setup OnCommand Unified Manager to collect capacity information from your clusters, and setup Harvester to retrieve those from UM to be stored in a time series database. From there you could interpret the data however you want.
You could also contact an account or sales representative to explore options for having our Professional Services team assist with this type of setup.
In addition to what experts have already said, this could be useful:
Not exactly what you need but may be handy: If you have OCUM monitoring your NetApp Storage (OCUM is free), then there are some useful reports , one such is - Volumes Capacity Growth report, that can give you an idea about 'Dialy growth rate (GB)' and 'Daily Growth rate (%)' along with 'Days to full' across all the cDOT/SVMs/Volumes. You can export this report in CSV/pdf/excel to email. Then sort it out for specific cDOT in excel. This could give you some idea about all the volume's growth rate.
Apart from this, if you are interested to know the growth of specific volume, (It'a manual task, don't know if there is another alternative) then good old 'snap-delta' is handy.
You can use 'snap-delta' command to view the rate of change between two Snapshot copies as well as the rate of change between a Snapshot copy and the active file system.
SANCL1::> volume snapshot show-delta -volume nfs_prod -vserver svm01 -snapshot1 Prod_09-10-2019_22.30.02.6379 -snapshot2 Prod_09-03-2019_22.30.02.3686 A total of 41450881024 bytes (10119844 blocks) are different. Elapsed time between the Snapshot copies: 7d 3s. SANCL1::>