If you have any volumes with UNIX security style, then usermapping needs to be configured. Also you need to do "vsever cifs create" (do not confuse it with "vserver active-directory create" which is something different!) to create a machine account in AD (it's not enough to just manually add a machine account into your AD domain). You can check the secd.log (you can get it via http://<netapp node IP>/spi ) for any errors regarding usermapping and/or security.
Of course if you have users in LDAP/NIS that you want to map to (instead of, say, just mapping all windows user to one specific UNIX user) then you need to setup LDAP/NIS as name service
But honestly, your partner (the one who sold you the NetApp) should be able to help you with that. Also, it's not often a good idea to use a single SVM for file and block storage at the same time. It's better to separate these into multiple SVMs
