SnapLock is a feature of aggregate. The SnapLock mode (compliance or enterprise) is inherited by the volume. So to have both: Compliance and Enterprise SnapLock you have to have 2 aggregates.
Also, you cannot use SnapLock aggregate for SVM root volume, which means in your case, you'll need total five aggregates (3 data aggregates):
- One non-Snaplock aggregate for SVM root volume (data aggr)
- One SnapLock Compliance (data aggr)
- One SnapLock Enterprise (data aggr)
- Two node root aggregates which living on partitions, no additional drives required here
I believe you by saying ADP v2 mean RD2 (Root-Data-Data Partitioning). RD2 supported only on SSDs, so with HDDs, you have only Root-Data Partitioning type of ADP. And yes, ADP is supported with SnapLock starting with ONTAP 9.0.