# Server — Properties, JVM, Operations

## Server properties (view-distance=8, simulation-distance=6)

`server_pack/server.properties` — set these values:

```properties
view-distance=8
simulation-distance=6
max-players=8
motd=SCICRAFT - The Dark Photon Protocol
difficulty=hard
spawn-protection=0
network-compression-threshold=256
enable-command-block=true
online-mode=true
```

`server_pack/eula.txt` → `eula=true` (after review).

## Recommended JVM Flags (server)

```bash
java -Xms4G -Xmx8G \
  -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 \
  -Dlog4j2.formatMsgNoLookups=true \
  -jar neoforge-21.1.248-server.jar nogui
```

Notes:
- G1 tuning keeps large-tech-server TPS stable under chunk gen (Krypton
  Reno + BadOptimizations help server-side).
- `-Xms4G` avoids early GC churn. Cap at 8G; this pack is RAM-hungry
  from AE2/Mekanism tick load but does not need 16G.

## Server start order

1. `packwiz install --dir server_pack` (first time / after changes)
2. Accept EULA.
3. Launch with the JVM flags above.

## Common failures

| Symptom | Fix |
|---------|-----|
| "Mismatched mods" on client join | Run `packwiz refresh` both packs, redeploy. |
| Sinytra connector errors | Update Sinytra Connector + Forgified Fabric API together. |
| Iris black screen | Disable flywheel compat first, then test without shaders. |
| Crash on world gen (Deeper and Darker) | Ensure CF 659011 + its lithostitched data load; update both. |
| TPS lag from many AE2 cells | Check FTB chunk claims; lower `simulation-distance`. |
| Immersive Portals won't load | Must be the Fabric jar added via `url add --force` (Modrinth blocks loader mismatch). |

## Backups

- World: copy `server_pack/world/` (or use FTB Chunks backups).
- Configs: `server_pack/config/` mirrors client defaults; keep both in sync
  when changing KubeJS scripts or FTB settings.