Stopping and starting of SAS servers / services is usually controlled by scripts as they need to be done in the right order. Simply re-booting physical servers will not ensure this.
Without knowing what your SAS server setup is, its a bit hard to give you the right advice, but the start order for servers is:
Metadata servers
Application servers
LSF services
Mid-tier servers
Environment Manager agents (if any)
Stopping is done in the reverse order.