Ah, one of my favorite topics, autogrow on NFS datastores with NFS...
First, let me address the Ontap autogrow settings. You can adjust when a volume autogrows via the registry
priv set diag;setflag wafl_reclaim_threshold_xl 90;priv set
That would need to be added to the filers rc file b/c it's a non-persistent setting
As for autogrow, 8.2 has autogrow / autoshrink which is a really cool feature which nees to be looked at if possible.
I was trying to follow your alerting.. Are you thin on thin? Wha'ts your snap reserve? If you are thin on thin, you are @ 75% Where are you getting 88%. 1.5TB out of 2TB are 75%.Also, from experience, if you are thin on thin you need to make sure you monitor overprovision and alarms on the vc side