Complex sentence: If more storage needs to be added, changes are to be made directly to the hardware where the applications are running on, causing downtime and introduces data responsibility to the application administrators, which is not an optimal responsibility model.
Split into simpler sentences: If more storage needs to be added, changes are to be made directly to the hardware where the applications are running on, causing downtime. It also introduces data responsibility to the application administrators, which is not an optimal responsibility model.