Did you check the NetApp comparability matrix whether 7.3.4 is compatible with 2008 R2 SP1... any hot fixes missing etc stuff. ?
are you using SnapDrive on server, if not i would suggest you to use SD on the server.
the best practice when you give out a LUN from netapp, its recommended that you have a SD installed on the server end.
when you discover a LUN from SD perspective, it has more control over that LUN rather than jus throwing out from Filer prespective