Why would an offline defrag take 40+ hours? Is this a 1989 server or something???
The last time I did offline defrags it took less than 4 hrs to do a 140GB database and that was on an old windows 2000 box. What version of windows are you on? What version of exchange?
You say this is an active/active/passive cluster, but you only mention 2 nodes.
Is this windows server 2000? You can move the store resource to another node, this is not a replication process. If you delete the public store and create a new one, it will have no folders. I don’t think that’s what you want. Replication would be necessary if you have another exchange server entirely (not another node of the same exchange cluster) to replicate to. What is your end goal for this public store? Do you want it off of this cluster altogether?
There might be a problem with the partition of your hard disk drive. Make sure that the drive is correctly formatted before applying any modifications on it.