Moving from one server to another.
PLANNING
Build the new server fully before touching the old one Replicate the configuration Test thoroughly with a hosts file entry before changing DNS
THE SEQUENCE
- Provision and secure the new server.
- Install and configure the same software stack.
- Copy files and import databases.
- Test with a hosts file entry, covering every application and function.
- Lower DNS TTL a day beforehand.
- Freeze changes on the old server if it holds transactional data.
- Take a final data sync.
- Change DNS.
- Keep the old server running for a week.
WHAT PEOPLE FORGET
Cron jobs SSL certificates, which need reissuing for the new server Mail configuration and reverse DNS for the new address Third-party whitelists referencing the old IP address File ownership and permissions after copying
AFTERWARDS
Verify every application, mail flow, scheduled task and integration individually.
Do not decommission the old server until everything has been confirmed working for several days.
