Server worlds only grow. Every exploration trip, elytra flight and new player adds chunks, and most of them are visited once and never seen again — but they still sit on disk, still get copied into every backup and still have to be managed by the server. Pruning is the practice of deleting those dead chunks with MCA Selector so the world shrinks back to the terrain your community actually uses. This guide covers the server side of the job: measuring honestly, choosing what is safe to delete, and the checklist that keeps players on your side.
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What pruning can and cannot do
Pruning removes chunks — typically terrain outside your world border or chunks where nobody has ever spent real time. It shrinks the world folder, which makes backups smaller and faster, server restarts and world loads lighter, and a future world upload much less painful. It does not fix a server that is slow because of entity farms, redstone or too many loaded chunks at peak hours; that is a performance problem, not a file-size problem. Be honest with yourself about which one you have before scheduling downtime.
Measure the world before and after
Do not prune on vibes. Before you touch anything, record the size of the world folder — the sum of its region, poi and entities folders — and the number of .mca region files in it. That pair of numbers is your baseline. After the prune, measure the same two numbers on the edited copy. The difference is the real result you can report to your players (“the world went from X to Y”), and it is also your sanity check: if the folder barely changed, your selection was not what you thought it was. Note that deleting chunks is not the only way to reclaim space — our guide to reducing world size also covers defragmenting region files, which rewrites them without the empty space left behind by earlier edits.
Choosing what is safe to delete
- Outside the keep area. Draw the line around spawn and your players’ bases — a world border makes this explicit. Everything outside it goes. The step-by-step selection workflow is in prune a world in MCA Selector.
- Chunks nobody lived in. The Chunk Filter can select by InhabitedTime — the time players have actually spent in a chunk. Fly-through terrain has an InhabitedTime of seconds; a mined, built or farmed area has much more. See MCA Selector filters for how to build the query.
- Old-version chunks before an update. Before a big Minecraft update, many servers delete unexplored old-DataVersion chunks so they regenerate with new terrain and structures — the same job as resetting chunks, done at server scale.
When in doubt, keep the chunk. Disk space is cheap; a deleted base is a community problem you cannot undo.
The player-notification checklist
Most pruning disasters are communication failures, not tool failures. Work through this list before the maintenance window:
- Announce the date and the maintenance window in advance, in the places your players actually read.
- Publish what will be deleted in plain language (“everything outside the world border”, “chunks nobody has built in”) — and a deadline for players to speak up about outlying builds.
- Ask players to log out somewhere safe inside the keep area, and to tell you about any far-away bases, farms or nether hubs.
- Stop the server and take a full backup of the untouched world (see our backup workflow) — and say how long you will keep it.
- Do the edit on a local copy, measure before/after, upload, start the server and verify the key locations yourself before reopening.
- Announce the result with the real numbers, and keep the pre-prune backup until at least one full play cycle has passed.
Safety rules that are not optional
MCA Selector writes deletions to the world files immediately — there is no save button and no undo, as explained in why MCA Selector changes are already saved. So: never edit the live server copy, never edit while the server is running, and never prune without the full backup from the checklist. Work on a downloaded copy, verify it, then upload it back during the window.
When pruning is not enough
If the world is still huge after an honest prune — or the real problem is a growing player count rather than dead chunks — the next step is usually the plan, not the world. A bigger RAM allocation and faster storage do more for a busy server than another prune. Compare the options in our Minecraft server hosting guide and size the RAM with the server RAM guide; if you are ready to look at plans, start with Apex Hosting for a beginner-friendly panel or Hostinger’s Game Panel plans if you want a full VPS under the panel.
Download MCA Selector 2.9
Every server-side job in this guide starts with a local edit. Get the current release from the MCA Selector download page — the Windows installer, the cross-platform .jar, the macOS .dmg and the Linux .deb/.rpm, every button pointing at the official GitHub release files with the SHA-256 checksum listed, plus a clearly labelled site mirror as a fallback. It is free and open source under the MIT licence.