- ONTAP 9.x
- Advanced Disk Partitioning (ADP)
- Root aggregate
It is not possible to remove disks that already assigned to an aggregate. One can convert a RAID-DP to RAID-4 which will release a disk as a spare at the cost of reduced redundancy.
On the other hand, it is not possible to unpartition a disk in an ADP partitioned shelf to use it as a physical disk in an aggregate.
More about root-data partitioning.