There’s a new official DR method on its way out which is way better than the HA one available just now but we can’t use it as it needs additional (expensive) SQL licences.
Our DR method is:
DNS entry for prod that we switch the IP address on if DR needs to be invoked
DR Server being completely blank (no BigFix installed)
SQL server for it on another server where there is SQL Log Shipping from the Prod
We then RoboCopy the required files (including custom site exports for Analysis and Fixlets) over to the DR server every 6 hours
When DR hits we stop log shipping, change the SQL server from Read Only to production, modify the IP address on the DNS entry and then fresh install BigFix. As all the relays are configured to use a hostname, everything falls over nicely (though not always the quickly).
If you can afford the SQL Always On then this would be the best way to go but it’s super expensive and you’ll need a few servers with it too.