Thanks for the reply! I have been successfully doing reverse resync since past 6 years without any issue and i know the difference between reverse resync and resync. But wanted to know what if someone does it wrongly. I had also given feedback to NetApp Team to avoid keeping both option of reverse resync and resync just next to each other but know success.
I was thinking about having clone backup of volume before doing reverse resync and resync, but what is fan-out\cascade snapmirror?
DR <---30 minutes Schedule----<DC>-----30 Minutes Schedule-----> NDR
So do you mean to say, If we are LIVE at DC side and want to reverse resync from DC to DR, we should first do snapmirror update from DC to NDR manually , so that we can have additional copy from DC to NDR so even if in worst case if we do resync from DR to DC and overwrite contents of DC with DR, we will still have additional copy of DC at NDR correct?
I am only confused with terms and your setup. But, your understanding of the fact that you have another copy of the destination volume as Territory copy and you can use that to recover if anything happens to source/dest is correct.
Normally, I would assume, this way:
Source Dest. DC (live) -------> DR
Source Dest. DC (live) <------- DR
Cascade is basically: DC DR TC Source (DC:DR) ----> destination ----> (DR:TC) Territory copy