Create a "hot backup" server machine?

[Ralph Dratman]

I'm trying to create an offsite "hot backup" of a FreeBSD server. If 
the primary server fails, I want to transport the spare machine to 
the existing site and bring it up as a replacement, with little or no 
reconfiguration necessary.

Nightly mirroring would be adequate in this situation. The system is 
not running live transaction processing or anything comparable.

Is there a straightforward, automated way to mirror a whole FreeBSD 
system, using open source software?

I'm testing ftpcopy to remotely mirror the files and directories. 
Ftpcopy performs an incremental comparison using dates and file 
sizes, which should minimize the nightly backup time and traffic 
load. So far that part seems to be working well.

But I haven't figured out how to get the users, groups and 
permissions mirrored. There are about 200 users. And there may be 
other gotchas I haven't thought of yet.

Thank you very much.

Regards,

Ralph