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Network & Bandwidth Guide

This document explains how SEBackup handles network transfers, bandwidth limiting, and provides recommendations for network topology in game server environments.

Why Bandwidth Limiting Matters

Space Engineers dedicated servers are sensitive to network congestion. When a large backup archive is being transferred across the network, it can:

  • Increase player latency (rubber-banding, warping)
  • Cause client timeouts and disconnects
  • Slow down game world synchronization
  • Interfere with other game servers on the same network

SEBackup provides bandwidth throttling to prevent backup transfers from impacting game performance.

Transfer Methods

SEBackup supports three transfer methods, in order of preference:

1. BITS (Background Intelligent Transfer Service)

Best for: Large transfers over reliable networks.

BITS is a Windows service designed for background file transfers. It automatically:

  • Throttles based on available bandwidth
  • Resumes interrupted transfers
  • Yields to foreground network traffic

SEBackup uses BITS when available and when max_bandwidth_mbps is configured.

[network]
max_bandwidth_mbps = 100   # BITS will limit to this rate

BITS is the recommended method because it is network-aware and automatically backs off when other applications need bandwidth.

2. Robocopy with Inter-Packet Gap (IPG)

Best for: Windows-to-Windows transfers when BITS is unavailable.

Robocopy's /IPG flag inserts a delay (in milliseconds) between each 64KB packet. This is a simple but effective throttle.

[network]
robocopy_ipg_ms = 20   # 20ms gap between 64KB packets

IPG to bandwidth approximation:

IPG (ms) Approx. Bandwidth Use Case
0 Unlimited Dedicated backup network
5 ~100 Mbps Light throttling
10 ~50 Mbps Moderate throttling
20 ~25 Mbps Standard throttling
50 ~10 Mbps Heavy throttling
100 ~5 Mbps Very conservative

These are rough approximations. Actual throughput depends on network conditions, disk I/O speed, and system load.

3. Copy-Item Fallback

Best for: Nothing (it is a last resort).

If neither BITS nor robocopy are available, SEBackup falls back to PowerShell's Copy-Item cmdlet. This provides no bandwidth throttling and is the slowest option. It is only used as a fallback to ensure the backup completes.

Configuration

All network settings are in Config\global.toml under [network]:

[network]
# Maximum bandwidth in megabits per second.
# 0 = unlimited (no throttling).
# 100 = limit to 100 Mbps.
# 50 = limit to 50 Mbps.
max_bandwidth_mbps = 100

# Robocopy inter-packet gap in milliseconds.
# Only used when robocopy is the transfer method.
# 0 = no gap (full speed).
# Higher values = more throttling.
robocopy_ipg_ms = 0

Choosing the Right Settings

Dedicated backup network (separate NIC/VLAN):

max_bandwidth_mbps = 0     # No limit needed
robocopy_ipg_ms = 0

Shared network, low-population servers (< 10 players):

max_bandwidth_mbps = 100   # Gentle throttle
robocopy_ipg_ms = 0

Shared network, active servers (10-30 players):

max_bandwidth_mbps = 50    # Moderate throttle
robocopy_ipg_ms = 20

Shared network, high-population servers (30+ players):

max_bandwidth_mbps = 25    # Conservative
robocopy_ipg_ms = 50

Metered / cloud connection:

max_bandwidth_mbps = 10    # Very conservative
robocopy_ipg_ms = 100

Network Topology Recommendations

Small Setup (1-2 servers on one machine)

[Internet]
     |
[Router/Firewall]
     |
[Switch] ---- [C&C + Game Server PC] ---- [NAS (optional)]

In this setup, the C&C and game server are the same machine (or on the same network). Backups transfer over the local network or locally on the same machine.

Recommendation: If the C&C and game server are the same machine, transfers happen locally and bandwidth limiting is less critical. Set max_bandwidth_mbps = 0 since no network traffic is involved.

Medium Setup (Multiple servers, one location)

[Internet]
     |
[Router/Firewall]
     |
[Managed Switch]
     |--- [C&C Server]
     |--- [Game Server 1]
     |--- [Game Server 2]
     |--- [NAS]

Recommendation: Use a gigabit switch. Set max_bandwidth_mbps = 100 to leave headroom for game traffic. Schedule backups during low-activity hours if possible (e.g., start_time = "04:00").

Ideal Setup (Dedicated backup network)

[Internet]
     |
[Router/Firewall]
     |
[Game Network Switch] (1Gbps or 10Gbps)
     |--- [Game Server 1] (NIC 1: game traffic)
     |--- [Game Server 2] (NIC 1: game traffic)
     |
[Backup Network Switch] (1Gbps)
     |--- [C&C Server]
     |--- [Game Server 1] (NIC 2: backup traffic)
     |--- [Game Server 2] (NIC 2: backup traffic)
     |--- [NAS]

Recommendation: With a dedicated backup network, set max_bandwidth_mbps = 0 (unlimited). Backup traffic will not affect game traffic because it flows over a separate physical network.

Remote / Cloud Setup

[Cloud / Remote DC]          [Home Network]
  |                               |
  [Game Server]---[VPN/WAN]---[C&C Server]
                                  |
                               [NAS]

Recommendation: This setup has limited bandwidth between the game server and C&C. Use aggressive throttling (max_bandwidth_mbps = 10-25) and schedule backups during off-peak hours. Incremental backups are especially important here to minimize transfer sizes.

Monitoring Transfers

Check Active BITS Transfers

Import-Module .\SEBackup.psd1
Get-SEBTransferStatus

Cancel a Transfer

Stop-SEBTransfer -NodeName "GamePC01" -InstanceName "PvPArena"

Transfer Performance Tips

  1. Use incremental backups. After the initial full backup, incrementals are typically 80-95% smaller. A 500MB full backup might produce 5-50MB incrementals.

  2. Compress on the node. SEBackup compresses archives on the compute node before transferring. This means you are transferring compressed data, not raw files.

  3. Schedule during off-peak hours. Set start_time in [schedule] to a time when few players are online (e.g., 2:00 AM - 6:00 AM local time).

  4. Use 7-Zip compression. 7-Zip typically achieves 10-30% better compression than .NET's built-in compression, resulting in smaller transfers.

  5. Monitor with load awareness. Enable [load_awareness] to automatically defer backups when the game server is under heavy load.