Even if IBM Planning Analytics with Watson (TM1) can handle massive amount of data, you get the requirement to either load or extract data from another system. It could be a data lake like the one from Azure or Amazon.

Connecting Microsoft Azure Data Lake into IBM Planning Analytics with Watson (TM1)

https://forum.cubewise.com/t/tm1-data-lake-exports-with-tm1py/4252

Azure Data Lake service