Catalyzes the production of glycerol under anaerobic growth conditions. Glycerol production serves as a redox sink by consuming the excess cytosolic NADH during anaerobic metabolism. NAD(+) + sn-glycerol 3-phosphate = dihydroxyacetone phosphate + H(+) + NADH By anaerobic growth conditions and other conditions leading to accumulation of cytosolic NADH. Leads to poor growth under anaerobic conditions (PubMed:9171333). Does not produce detectable glycerol, is highly osmosensitive and fails to grow under anoxic conditions, when GPD1 is also deleted (PubMed:9171333). Present with 8966 molecules/cell in log phase SD medium. Belongs to the NAD-dependent glycerol-3-phosphate dehydrogenase family. It is uncertain whether Met-1 or Met-49 is the initiator.