There are several ways you can control access to a SAN volume:
Unmount a volume on client computers that shouldn’t have access to it (using the xsanctl command-line tool). However, users who have administrator accounts on client computers can browse and mount SAN volumes.
Specify owner, group, and general access permissions in the Finder.
Control user access to files and folders on a volume, by setting up access control lists (ACLs) in the Server app. This only works if access controls lists are enabled for a volume.