SCM Admin just need to start Broker [bkrd] process by executing $CA_SCM_HOME/bin/bkrd - that will start other necessary processes.
When $CA_SCM_HOME/bin/bkrd is executed, it first will try to connect with an rtserver process if it already exists. If rtserver is not running, then it will start the rtserver process.
Once it is connected to the rtserver, it will then start a number of hserver processes based on the "-minserver" setting in $CA_SCM_HOME/HBroker.arg.
SCM Admin can also monitor those processes on regular basis as well as to stop gracefully.