When you do a new SAS 9 install, there are a number of distinct user id’s that have to be created, which map to specific roles within the SAS 9 environment. While you can change the default usernames, it is recommended that you create and use these distinct user id’s rather than using a single (or combined) id.

The required user id’s are:
sasadm – The SAS Administrator user id should be created on your metadata server machine. This user has privileges to manage user accounts in metadata and administer the metadata server. The SAS Administrator has unrestricted access to the metadata and this user ID should be protected accordingly. This ID should only be used for the SAS Management Console application.

sassrv- The SAS General Server user id should be created on your server machines. You must make the SAS security group its default group. This account will be used by the object spawner to launch stored process servers. This account will need access to any OS resources required to run stored processes. The default configuration of the SAS 9.1 Intelligence Architecture creates this single account for load balanced, stored process server usage. Additional server accounts can be created to give different levels of access as required.

sasguest- The SAS Guest user id will need to be created on your metadata server machine. This user is a generic user account and should have the lowest level of security privileges. This user id is used by the SAS® Information Delivery Portal to log users into the public kiosk area.

sastrust- The SAS Trusted User will be created on the metadata server machine. Because this user ID is a trusted ID, SAS servers such as the OLAP server and mid-tier applications can use this ID to impersonate authenticated clients on the metadata server; that is, the servers can communicate with the metadata server on behalf of the clients. This is a highly privileged account and should be protected accordingly.

sasdemo- The SAS Demo User will be created on your metadata server machine. This user has permission to demonstrate the SAS software you have installed and to verify the configuration.

saswbadm- The SAS Web Administrator will be created on your metadata server machine. You need only create an account for the Web administrator if you will be installing web applications, such as SAS® Web Report Studio, SAS® Web Report Viewer, or SAS Information Delivery Portal. This user has permission to administer the SAS Web infrastructure.

This information was sourced from Sugi 29 – Paper 225-29

Top Deployment Considerations for the SAS® 9.1 Intelligence Architecture

Which also provides a great overview of how the whole SAS 9 environment hangs together, check it out.