What you do when the server is gone.
THE SCENARIOS
Hardware failure A compromise requiring a rebuild Accidental deletion of the server A failed upgrade leaving the system unbootable Data corruption
WHAT YOU NEED TO RECOVER
Backups stored independently of the server Documentation of the configuration Credentials stored elsewhere A record of what was installed and how
THE DOCUMENTATION THAT MATTERS
Which software is installed and its versions Configuration decisions and non-default settings DNS records and where they are hosted Third-party services and their credentials Cron jobs
Keep this off the server, updated when things change.
RECOVERY TIME
Be realistic. Rebuilding a server from scratch and restoring data takes hours at best, longer if the documentation is incomplete.
If your business cannot tolerate that, you need a faster arrangement: a standby server, or a managed service with a recovery commitment.
TESTING
Rebuild from documentation and backups once, on a test server. You will find gaps, which is the point.
