I currently have a synchronization system of 300 users.
I save the configuration files and the PostgreSQL database every day on another server.

Some questions:
What is the best way to restore the system in case of a server crash?
If I rebuild a new server without restoring the database and using a LDAP group, how long does it take for the database synchronization is complete for all 300 users?
What is the best practice ?
What is the best practice for a maintenance routine to keep it in tune ?

Thx for your ideas