I inherited a 'creaky' legacy system - and the server needed to be rebooted. It hadn't been rebooted in 5+ years.
I did all of the sensible things: I checked that the backups were up to date - and then I manually copied the entire codebase and local data and database to another server before touching anything, just to be sure.
After a lot of tracking down I discovered that a previous developer had placed critical config in
I then discovered that the backup system was configured to ignore
That took a lot of effort and guesswork to rebuild.
Now I always copy