Key takeaways
- Test a restore before you need one. An untested backup is not a backup.
- Keep at least one copy off the machine that runs the server.
- Back up the mod list and configs as well as the world, or the restore will not load.
Every server owner has a backup schedule. A much smaller number have ever restored from it, and the gap between those two groups is where worlds get lost.
What to copy
The world folder is the obvious part. The less obvious part is everything needed to load it: the mod or plugin list at matching versions, the configuration folder, and the server properties file.
A world restored into a different mod set will either fail to start or start and silently remove content. That is the failure mode people discover at the worst moment, and it is the reason a backup should be a snapshot of the whole server directory rather than just the map.
Where to keep it
At minimum, somewhere that is not the same disk. Ideally somewhere that is not the same machine. A host that offers automated snapshots is convenient and is not a substitute – if the account goes away, so do the snapshots.
For a small server, a nightly copy pulled down to a home machine is enough, and it is the copy that will still exist after a billing mistake.
How often
Match the interval to how much work you are willing to redo. A server where people build for three hours an evening loses an evening with a daily backup, which is usually acceptable. A creative server working toward a deadline wants hourly.
Keep more than one generation. A single rolling backup will happily overwrite your good copy with a corrupted one at 3am.
The restore test
Copy the backup to a second directory, start it on a different port, join it, walk around, check a build you know. Twenty minutes, once, before you need it.
Our experience is that the first restore test almost always finds something: a missing config, a plugin version mismatch, a world folder that was being written while it was copied. Finding that on a Tuesday afternoon is a minor annoyance. Finding it after corruption is a lost server.
One backup you never rotate
Keep a permanent copy from before every mod list change and every game version update, and never delete it. Chunk corruption from a bad update can take weeks to notice, by which point every rotating backup contains the same problem.
Backing up while the server runs
Copying a world folder while the server is writing to it produces files in an inconsistent state. The safe options are to save-off and flush before the copy, to use a plugin that handles the pause automatically, or to snapshot at the filesystem level if your host supports it.
The failure this prevents is subtle: the backup completes, reports success, and contains a region file written halfway. You find out months later.
How many generations to keep
Three is a reasonable floor – yesterday, last week, last month – plus the permanent pre-update copies. Storage is cheap relative to the work a world represents, and the only backup that has ever mattered is the one from before you noticed the problem.
What to do when something breaks
Stop the server before touching anything. A corrupted world being written to by a running server gets more corrupted. Copy the current state aside even if it is broken – it may contain recent work you can merge back in – and then restore into a fresh directory rather than over the top of the damaged one.
Chunk-level damage can often be repaired by deleting the affected region files, which regenerates that terrain and loses whatever was built there. That is a last resort and it is a good reason to know which region files correspond to which builds before you need to.
The non-technical part
Tell players the backup schedule. A community that knows work is saved nightly behaves differently from one that suspects nothing is – people build bigger, and they panic less when something goes wrong. It also sets the expectation that an hour of lost work is possible, which is easier to accept in advance than after the fact. The rest of the day-one setup is in the first week guide.
Backups are not version control
A backup restores a moment. It cannot merge two states, and it cannot give you yesterday’s build with today’s terrain. Anyone hoping to undo one player’s work without losing everyone else’s is asking for something a world backup does not do.
For that, the answer is a block logger with rollback, which is a moderation tool rather than a disaster recovery one – covered alongside the other day-one decisions in the first week guide.
Images: Awesome Dungeon project gallery on Modrinth.