Thanks Joe for super response to Backup thread some day before, but I've started this new one due to little differencies.
My scenario is:
I got 3 servers.
First one is main server serving all of our clients websites (about 100 Joomla installations). Second one is secondary DNS and secondary MX server for first main server. Third is configured exactly the same as first one, but it is on different line (hosting provider) and is "sleeping" (serving only testing projects for now).
I am doing backups every day onto 2 different places from main server to third box and to our fileserver in office (with thin upload line) - paranoic ... I mean virtualmin virtualservers backups.
In the case of main server failure ... (atomic bomb or something like that).
I hope (and have tested) that secondary MX is holding emails and waiting for first one server to come up and than deliver them.
Than - while I am in panic and calling for new hardware - I will restore backups on third server.
Our clienst are using our DNS servers for their domains. So we will only chagne GLUE for our primary nameserver. I will restore first domain (our main domain with nameservers) - but I don't know how will second server behave. Should I delete all virtualhosts secondary DNS (slave) files on second server? - Than I can start restoring backups and everyghing should work (if the will of computer god only can pass this ;o)?
I hope that you understand my problem and my scenario and someone could find this case as helpful in future. If you don't understand me or have some questions - please help me to specifie this problem more deeply - so we all can find solution for this - I know that this can save some poor administrator a**.
We aren't rich company so we can't afford highly available cluster systems for this moment (but I am doing some little research myself for establishing something like this based on web && virtualmin).
Thanks for any advices. Many thanks.