Tony Redmond, in his post, discusses the available options for moving a database between DAGs. “Though the unbreakable connection that exists in all previous versions of Exchange to tie a database to a specific server no longer exists”, he says, “the notion of a totally portable database is not yet implemented.”
He gives a couple of options to accomplish the task of moving the database. One is to use the move mailbox function to move all the mailboxes from the database to a database or databases in the second DAG. However, this is not easy for large number of mailboxes or for moving multiple databases between DAGs. The second idea, proposed by Tim McMichael of Microsoft, is that it would be possible to use a “swing server” to transport the database from one DAG to another.
Steps involved would be:
- Commission a specific mailbox server and introduce it into the first DAG.
- Transfer a copy of the mailbox database to be transferred to that server and make it active.
- Remove all other copies of the mailbox database so that the only copy is now present on the swing server.
- Remove the swing server from the first DAG and add it to the second DAG before completing the process by creating whatever number of additional copies of the database are necessary in the second DAG.
- Finally, you remove the copy of the database from the swing server and remove it from the second DAG.
Obviously, there are some downsides to the swing server technique. First, it requires additional hardware. Second, there will be a time when the mailbox database (or databases) lose redundancy as you have to reduce them to just one copy before it’s possible to move between DAGs. The redundancy can be reintroduced as soon as the databases join the second DAG but even so, it will take time for the copies to be seeded. Last, this is a moderately complex multi-step technique.
Which method to use will be your call depending on the situation.