We report on the laser performance and power scaling properties of diode-laser side-pumped Nd:YAG rod lasers operating at high cw output powers. Applying a pump power of 1100 W cw in a ninefold pump geometry, we obtain an output power of more than 300 W in multimode operation. For a comparable pump scheme an output power of more than 45 W in TEM00 mode operation is realized with an optical-to-optical efficiency of more than 11\%.