What is parent partition?
A parent partition is a logical hard drive division in the Microsoft Hyper-V environment that's responsible for running the hypervisor layer and creating and managing child partitions.
In Hyper-V, there are three possible types of partitions: the root partition, the parent partition and the child partition. (In Microsoft Hyper-V version 1.0, however, the root and parent partitions are a single entity.) Each partition has its own memory and processor resources as well as policies on device use.Content Continues Below
The root partition is the original partition. It starts the hypervisor. The parent partition can call the hypervisor and request the creation of new child partitions. Virtualized operating systems (guest OS) and applications run in child partitions. There can be only one parent partition on a given machine but there can be as many child partitions as computing resources will support.