We just recently migrated to an Exchange 2010 server. Currently all of the roles and mailboxes are installed on 1 server (we are a small company with less than 100 users). I am wanting to use DAG for replication however it seems most set ups for DAG requires at least 3 or 4 total servers. Is there anyway to make this work with just two servers and both of these servers would have all the roles and mailboxes? Maybe there is a better way to do this than DAG? I'm open for suggestions.

The goal here is to have some sort of replicated server so that if there is an issue with our primary Exchange server, another one can be brought up within an hour or so with all current information (not a backup). It doesn't necessarily have to be instantaneous.