There is a particular kind of confidence people have right before they break a working server. It usually sounds like, this will only take a minute. That is exactly when a proper backup matters most.
This guide explains how to back up a Linux server properly before making risky changes such as upgrades, control panel installs, migrations or major configuration edits.
Define what needs protecting
Depending on the server, that may include the database, web files, mail data, application configs, SSL certificates and custom service files. A backup that misses the important bits is just a comforting lie.
Take both data and configuration copies
Restoring files without the surrounding configuration can still leave you with a broken service. Capture enough of the environment to rebuild what matters.
Know your rollback route
If the change fails, will you restore from snapshot, replace files, revert a package or rebuild from backup. Decide this before the maintenance begins, not after the error messages start.
Final thoughts
The safest time to think about recovery is before you need it. Back up first, change second and test your assumptions before production has a chance to punish them.