The SAS 9.4 Administration Guide is the place to look. This page should be useful to you. SAS server logs are text files written to the SAS install folders on your SAS servers by default.
Note that workspace server logs contain only startup and shutdown code by default; everything else is routed to the client. You have to modify the logconfig.xml file to also record user's actions server-side.
The SAS Users Group for Administrators (SUGA) is open to all SAS administrators and architects who install, update, manage or maintain a SAS deployment.