In Mac OS X and Mac OS X server, when creating files and folders, group ownership is automatically set to match the group ownership of the parent folder. However, by default, Xsan volumes have their group ownership set to "wheel". As a result, all files and folders created on an Xsan volume have group ownership set to "wheel".
If this does not suit your site's workflow, manually change a folder's group ownership to another group in the Finder.
After changing the group ownership on a folder, all files and folders created within the folder will have group ownership set to match the parent folder's group ownership.