I pull backups using rsync over ssh, with a restricted account, from a cronjob. Well, I don’t, but one of my mods does. I take and download a backup when I do an update. So, in the one case we could lose a few days of forum activity, and in the other case we could lose a month or more.
I should probably set up a crontab of my own. I could also increase the frequency of backups - presently set to 2 days.
In both cases we have to be moderately competent admins of our own systems. We should only lose the forum if both of us lose our downloaded copies and our own backups as well as the server itself.
Edit: good point, one must have some positive check that the process is working, and some idea, however shallow, that the downloaded backups are good.
I haven’t taken special care of the domain: ideally that too would have dual administration and joint ownership of some sort. If we lost control, the forum would have to reappear on a new domain - it could send digests and notifications to the members by email, so with a bit of trust they could rejoin.