Joyce -
Given that I'm teaching MetroCluster for a client in India this week this post realy caught my attention !
Best guess is that there was an unkown failure of the cluster, and the systems weren't sure of the state before the failure.
It was probably a check to prevent a bad resync if there was a split brain scenario.
I'd want to check the logs on both sides of the cluster to see what happened before the break.
I probably would have isolated the down system and done this before proceeding with bringing the failed node back online.
Thank you for this timely question.
I'll probably use it as a teaching example in the morning.
I hope this response has been helpful to you.
At your service,
Eugene E. Kashpureff, Sr.
Independent NetApp Consultant http://www.linkedin.com/in/eugenekashpureff
Senior NetApp Instructor, IT Learning Solutions http://sg.itls.asia/netapp
(P.S. I appreciate 'kudos' on any helpful posts.)