Parabola-class freighter
From Halopedia, the Halo wiki
The Parabola-class Freighter is a United Nations Space Command starship classification used in the early 2626. However by 2525, many of these freighers were independant and used for commercial and civilian use. They were relavively simple craft, with large storage bays, and rotating sections. The rotating sections contained water tanks that would automatically irrigate crops grown in the hydroponics bay in the middle of the vessel.
Vessels of this class included the Laden.