Why RPN table spaces instead of the already-existing table spaces types in DB2?
The simple answer is the ability to grow the amount of data you store. RPN table spaces enable you to store large amounts of data. The DSSIZE can grow up to 1 TB for a partition. And the maximum table size increases to 4 PB with up to 256 trillion rows per table. That is a lot of data that can be stored! Think about it this way: if you were to insert 1000 rows per second it would take more than 8000 years to fill the table to capacity!
With RPN table spaces you get the ability to create larger partition sizes. The maximum partition size is now 1 TB (it used to be 256 GB). So if you are reaching the capacity size of existing table space options, RPN table spaces will allow you to store a LOT more data. Of course, this requires an expanded RID, which increases from 5 bytes to 7 bytes. So that will impact the DDL for the mapping table for your online REORG utilities.
You can find more information on DB2 RPN Table space online here.