CMDBuild READY2USE 3.3.2 e max number of session

we have downloaded and installed CMDBuild READY2USE 3.3.1 Appliance then upgraded to 3.3.2 (3 different vm with capacities equal to recommended) , we are evaluating it and applying some crash test (100 users/ramp 1 second), we obtain just some complete ReqFulfill tickets, the others are not complete, seem like zombies. Seems like we reach the max number of connection allowed by DB. Can we overcome this ostacle?