We have completed OnTap Upgrade from 9.6p9 to 9.7p8 following Upgrade Advisor. Everything looks good, no any errors in any logs. After checked vSphere (NFS datastores), there are no any errors/issues neither. OCUM or Event Log didn't indicate any issues.
After a week or so, they experienced some performance issues with a few particular VM's among thousands VM's, and then they suspect these are caused by Upgrade, and ask Storage people to look into it. OnTap covers almost everything, people can relate any issue to it without presenting any evidences or any indications, it is like "presumption of guilty" to me. Of cause, I don't want to say that to them.
But, what should I say, what my professional response should be? I hope some experts here can help me.
