System Requirements

Server Requirements

Operating System

• Ubuntu 20.04 LTS, 22.04 LTS, or 24.04 LTS (recommended)
• Debian 11 (Bullseye) or 12 (Bookworm)

Other Linux distributions may work but are not officially supported.

Hardware (Minimum)

Resource	Master	Slave
CPU	1 vCPU	1 vCPU
RAM	1 GB	1 GB
Disk	20 GB	Same as master

Hardware (Recommended)

Resource	Master	Slave
CPU	2+ vCPU	2+ vCPU
RAM	2+ GB	2+ GB
Disk	SSD, 2x WordPress size	Same as master

Software Stack

The master server must have:

• Web server: Nginx or Apache
• PHP: 7.4, 8.0, 8.1, 8.2, or 8.3
• Database: MySQL 5.7+, 8.0+ or MariaDB 10.3+
• WordPress: Any recent version

The slave server should match the master's software versions. If software is missing, Tergum can auto-install it during setup.

Network Requirements

Outbound Access (Required)

Both servers need outbound HTTPS (port 443) to:

• app.tergum.ca - Tergum API
• login.tailscale.com - Tailscale coordination
• *.cloudflare.com - Cloudflare services

Inbound Access

• No inbound ports required on either server
• All communication uses outbound connections
• Works behind NAT, firewalls, and residential internet

Bandwidth

• Initial clone: depends on WordPress size (plan for 10-100 MB/min)
• Ongoing replication: minimal (a few KB/s for typical sites)
• Heartbeats: ~1 KB every 30 seconds

Third-Party Accounts

Cloudflare (Required)

• Free tier is sufficient
• Domain DNS must be managed by Cloudflare
• API token with Zone:DNS:Edit and Account:Cloudflare Tunnel:Read permissions

Tailscale (Required)

• Free tier supports up to 100 devices
• Used for secure server-to-server communication

WordPress Requirements

Supported Configurations

• ✅ Single-site WordPress
• ✅ WordPress Multisite (subdirectory mode)
• ⚠️ WordPress Multisite (subdomain mode) - requires additional DNS setup

Plugin Compatibility

Most plugins work normally. During failover, plugins that require:

• Outbound API calls: will work if slave has internet
• Local file writes: may have delayed sync (few seconds)
• External services: depend on those services

Known Incompatibilities

• Plugins that modify .htaccess dynamically
• Plugins with hardware-locked licenses (may need reactivation)
• Real-time collaboration plugins (may lose recent changes)

Pre-Flight Checklist

Before starting setup, verify:

• Two servers meeting hardware requirements
• Ubuntu/Debian installed on both
• Root SSH access working
• WordPress running on master
• Cloudflare account with domain added
• Tailscale account created
• Tergum account registered