Add drive enclosures to expand the configuration and to add large form factor drives to the configuration. Drive enclosures can be ordered separately for installation in the field, or they can be factory configured in a rack. Drive enclosures are optional. Because the Storage Base products and the Upgrade Node Pair include small form factor drive bays, the minimum configuration does not require any additional drive enclosures. For larger configurations, attach drive enclosures. Each drive enclosure includes 24 drive bays. The HP 3PAR StoreServ 7200 supports up to five (5) added drive enclosures. The HP 3PAR StoreServ 7400 supports up to nine (9) added drive enclosures per node pair. The two drive enclosure types can be intermixed in a single array.