IN pricciple this should work, whether the product is working is a different matter.

We do the same things with SAN replication, the SAN copies itself bit by bit to another SAN in the DR site, if site1 fails then we just start the database on the other site, it works and works well. At the same time the link between the SANs is broken.

Do you possible have a case where the file is still being written to as it is open by the second instance?

Worth pointing out again that ALL committed transactions are on disk somewhere, what is in memory doesnt really matter.

So the principle is sound, product sounds dodgy