How long does a single transaction take to run to completion? If the single transaction takes 15 seconds you would need approximately 12 vusers running for your scenario. (2800 trans per hour / 60 = 47 transactions per minute. 47 trans per minute / 4 ( 60 seconds / 15 seconds estimated trans time) = 12 vusers. Set your controller to run scenario by group, ramp up the 12 users and set the duration to 8 hours. With the script highlighted, click on the details tab. Click on more to get to the command line. Type -infiniteiterations to insure you have enough iterations and you should be good to go.