Oracle Partitioning and parallel DML

Can someone help to understand the Parallel DML doing INSERT and partitions? I had two partitioned table with 7 partitions in one table where Insert is going  and 5 partitions in the second table which is used in SELECT Using session level force Paralle DML 5INSERT /APPEND/ into 7_part_table select from 5Part_table This is Oracle Exadata, 2 two node RAC with 12.1. I can see that the above insert create more than 20 connections and causing a high bottleneck to the system Resource and affecting the other process. Is it suppose to create these many processes. DOP is manualTable/corresponding Index Level Degree is set as 1  TIASanjay

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