Physical and logical deletion

Physically deleting a segment prevents further access to that segment using its physical parents.

Physically deleting a segment also physically deletes its physical dependents, however one exception to this exists: If one of the physical parents of the physically deleted segment is a logical child that has been accessed from its logical parent, then the physically deleted segment is accessible from that logical child. The deleted segment is accessible from that logical child because the physical dependents of a logical child are variable intersection data.

Logically deleting a logical child prevents further access to the logical child using its logical parent. Unidirectional logical child segments are assumed to be logically deleted. A logical parent is considered logically deleted when all its logical children are physically deleted. For physically paired logical relationships, the physical child paired to the logical child must also be physically deleted before the logical parent is considered logically deleted.