Panel•4 min read

What is Aikar Flag and How to Change Your Startup Command

Learn about Aikar flags - optimized JVM flags for Minecraft servers that improve performance and reduce lag. Plus, how to customize your startup command in the panel.

What is Aikar Flag?

Aikar flags are a set of optimized JVM (Java Virtual Machine) flags specifically designed for Minecraft servers by Aikar, a well-known developer in the Minecraft community. These flags optimize garbage collection and memory management, resulting in better server performance and reduced lag spikes.

G1 Garbage Collector - Uses the G1GC which is optimized for applications that need low pause times

Memory Pre-allocation - Allocates all memory upfront to prevent allocation delays during gameplay

Optimized GC Settings - Fine-tuned garbage collection parameters for Minecraft's specific memory usage patterns

Reduced Lag Spikes - Minimizes pauses caused by garbage collection, resulting in smoother gameplay

About RAM Usage in Panel

When using Aikar flags, your RAM usage in the panel will display ~100% constantly. This is completely normal and intentional!

Aikar flags use -Xms and -Xmx with the same value, which tells Java to allocate all available memory upfront. This prevents memory allocation delays during gameplay and optimizes garbage collection. If your server needs more memory than allocated, the system will use swap memory automatically.

Important Note

Make sure to set the RAM value in the Aikar flags to match your server's allocated RAM in the panel. Using more RAM than allocated may cause your server to be terminated by the system.

Not Recommended for Proxies

Setting -Xms and -Xmx to the same value is NOT recommended for proxy servers like Velocity, BungeeCord, or Waterfall. Proxies have different memory usage patterns and typically benefit from dynamic memory allocation.

For proxies, use different values like -Xms512M -Xmx1024M instead.

Recommended Use Cases

Aikar flags are best suited for the following server types:

Vanilla Minecraft - Standard Minecraft servers without modifications

Spigot / Paper / Purpur - Plugin-based servers for survival, minigames, or factions

Fabric / Forge - Modded servers with heavy memory usage

Modpacks - Servers running modpacks like ATM, RLCraft, or Create

NOT for Proxies - Velocity, BungeeCord, Waterfall should use different flags

Aikar Flag Generator

Enter your server RAM allocation:

Generated startup command:

java -Xms4096M -Xmx4096M --add-modules=jdk.incubator.vector -XX:+UseG1GC -XX:+ParallelRefProcEnabled -XX:MaxGCPauseMillis=200 -XX:+UnlockExperimentalVMOptions -XX:+DisableExplicitGC -XX:+AlwaysPreTouch -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 -jar server.jar nogui

How to Change Your Startup Command

Follow the video tutorial or step-by-step guide below to change your server's startup command and apply the Aikar flags.

Video Tutorial

Step by Step Guide

Login & Select Server

Go to panel.syncara.host and login with your account. Click on the server you want to configure.

Navigate to Startup

On your server page, scroll down in the sidebar on the left side until you find the Startup menu, then click it.

Find Edit Startup Command

In the Startup page, scroll down until you find the Edit Startup Command section. This is where you can customize your server's startup command.

Paste Aikar Flags

Copy the generated Aikar flags command from the generator above and paste it into the startup command field. Make sure the RAM value matches your server's allocation.

Save & Restart

Click Save to apply the changes, then go back to Console and click Restart to restart your server with the new startup command.

Done!

Your server is now running with optimized Aikar flags. You should notice improved performance and fewer lag spikes during gameplay.

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