Snap servers are able to pull user lists from an NT domain (or Samba PDC), or are also capable of participating in an active directory domain. If you don't have a domain, "local" users can be added manually to the server.
Disk space can be carved into one or more volumes, then the volumes divided into one or more "shares". Example create a single volume called "volumeA" then create on that volume a share called "share1" then goto the security tab and find the share you created (share1) click on the "access" button and add whatever domain or local users and groups. Users and groups can have full access, or read only access and can access the files and folders via afp, smb, nfs, ftp. (All dependent on how you set the server up).
Here is a link to the adaptec admin guide
http://www.adaptec.com/en-US/support...gos_ug_pdf.htm