6027-1879 [E] Cannot remove pdisk pdiskName because arrayName is
the only remaining declustered array with at least number pdisks.
Explanation
The command failed to remove a pdisk from a declustered
array because no other declustered array in the recovery group has
sufficient pdisks to store the on-disk recovery group descriptor at
the required fault tolerance level.
User response
Add pdisks to another declustered array in this recovery
group before removing pdisks from this one.