MSA2000 3.5-inch drive enclosure. This 2U unit has twelve LFF (3.5-inch) drive bays and accepts for MSA2 dual-ported SAS and SATA drives. One model (AJ749A) has a single I/O module that matches with a single controller array head, giving a single path to the drives. The second model (AJ750A) comes standard with two I/O modules installed, required when paired with a dual controller array head, giving two paths to the drives for higher availability.