SMA is system management. For the application we have the backgroud process which is done by agents automatically. For agent functionalities and tracing we need SMA. And if we want to know how many logins are into our application we need SMA. Main activity is for agents.
SMA is utility to manage, monitor and control caches, agents, requestors, listeners, and other processing for all configured nodes. Please find the below useful links which will provide detail explanation about SMA.