Aikar's Flags for Minecraft Servers

WinterNode auto-applies tuned JVM flags to new Minecraft servers, so most servers already have the right flags with no setup. This guide shows how to check your flags, add Aikar’s flags on an older server, or replace them with your own.

Check your current flags

1. In the Game Control Panel sidebar, click Server Options
2. Find the JVM Flags field
3. If it already holds a long line starting with -XX:+UseG1GC, your server is set up and you do not need to change anything

Add Aikar’s Flags manually

Use these steps only if your JVM Flags field is empty, usually on a server created before June 29, 2026.

1. In the Game Control Panel sidebar, click Server Options
2. Copy the flags below and paste them into the JVM Flags field:

-XX:+UseG1GC -XX:+ParallelRefProcEnabled -XX:MaxGCPauseMillis=200 -XX:+UnlockExperimentalVMOptions -XX:+DisableExplicitGC -XX:G1NewSizePercent=30 -XX:G1MaxNewSizePercent=40 -XX:G1HeapRegionSize=8M -XX:G1ReservePercent=20 -XX:G1HeapWastePercent=5 -XX:G1MixedGCCountTarget=4 -XX:InitiatingHeapOccupancyPercent=15 -XX:G1MixedGCLiveThresholdPercent=90 -XX:G1RSetUpdatingPauseTimePercent=5 -XX:SurvivorRatio=32 -XX:+PerfDisableSharedMem -XX:MaxTenuringThreshold=1 -Dusing.aikars.flags=https://mcflags.emc.gs -Daikars.new.flags=true

3. Click Save
4. Click Restart to apply the change

Your startup command updates automatically. You should notice fewer lag spikes and more stable memory after the restart.

Use your own flags

WinterNode never overwrites JVM flags you set yourself. To use a custom set, paste your flags into the JVM Flags field, click Save, then click Restart. Your flags always take priority over the automatic ones.

What Aikar’s Flags Do

Your Minecraft server shares its RAM with Java itself. Java needs some of that RAM for a background task called garbage collection (GC), which clears out data the server no longer needs.

Without Aikar’s Flags, the server can use up so much RAM that Java runs out of room to do garbage collection. This causes lag spikes when GC runs, or an out-of-memory (OOM) crash when it can’t run at all.

Aikar’s Flags fix this by telling Java how to split RAM between the server and GC. They set aside enough memory for GC to run smoothly, so your server stays stable.

Why Overhead Matters

“Overhead” is the RAM reserved for Java’s internal tasks (garbage collection, class loading, and other background work). It is not available to the Minecraft server itself.

WinterNode reserves approximately 1.5 GB of overhead on plans that need it. Aikar’s Flags help Java use that overhead efficiently, so your server gets the most out of its remaining RAM.

Further Reading

For a full technical breakdown, see the Aikar’s Flags documentation on Paper Docs.