Setting up a "hot backup" server

Setting up a "hot backup" server

We run Zoho Analytics On-Premise, with a license for two servers, one each in two different physical locations. We run one location "primary", with the other site serving as a "hot backup" that can be switched to if something happens to the primary site. While some services need up-to-the-second syncing, for Zoho Analytics it's OK if the data on the backup is slightly stale (say, a day old).

I'm trying to figure out the best way to setup a "hot backup" of Zoho Analytics. Naively, seems like something like this would be the way to go:
  1. Backup site is usually not running.
  2. Cronjob shuts down the primary site at night.
  3. Use rsync to to sync the Zoho Analytics directory from the primary to the backup.
  4. Restart primary.
  5. If primary site goes down, startup the backup site.
This won't work completely, though. For one thing, both servers need their own license, and presumably I need to do something to prevent the rsync from overwriting the backup's license. Would excluding the 'conf' directory from the rsync be sufficient for this?

Maybe syncing just a subset of the Zoho Analytics directory (e.g. just the database) would be better?

Maybe there is some better way to do this?

Maybe there is a document that explains this that I cannot find?