ADR-001: Ginnungagap Connectivity
Project: Ginnungagap — Offsite Backup & Disaster Recovery
Decision status: Accepted
Implementation status: Deferred
Original design: VLAN 700, superseded before deployment
Context
Section titled “Context”OnyxNet requires a future offsite backup solution that can protect two categories of data:
- TrueNAS SCALE datasets
- Proxmox virtual machine and LXC backups
The intended destination is a dedicated backup NAS hosted at a geographically separate location.
An early design considered dedicated site-to-site networking infrastructure, including:
- VLAN 700, named Ginnungagap
- A proposed
10.0.10.0/31transit subnet - Additional remote routing and switching equipment
- Encrypted connectivity between sites
VLAN 700 was a proposed network segment, not a VPN by itself. The original concept also required a method of establishing cross-site connectivity.
Options Considered
Section titled “Options Considered”Option A: Dedicated site-to-site network
Section titled “Option A: Dedicated site-to-site network”Establish a routed connection between the two locations using dedicated networking infrastructure and an encrypted site-to-site tunnel.
Advantages
- Greater control over routing and network boundaries
- Opportunity to explore site-to-site network engineering
- Flexibility for future cross-site services
Disadvantages
- Additional equipment expenses under the original plan
- More remote components to configure and maintain
- Greater operational complexity
- More potential failure points
Option B: Host-to-host Tailscale connectivity
Section titled “Option B: Host-to-host Tailscale connectivity”Use Tailscale on the backup endpoints to establish encrypted connectivity over the existing Internet connections.
Advantages
- No additional dedicated remote routing equipment required for the intended backup use case
- Simplified deployment and ongoing management
- NAT traversal capabilities
- Access can be restricted to designated backup hosts and services
Trade-offs
- Reliance on Tailscale’s coordination infrastructure
- Direct connectivity is not guaranteed in every network environment; relaying may sometimes be necessary
- Endpoint identity, authentication, access control, and availability still require careful management
Decision
Section titled “Decision”Use Tailscale as the connectivity method for the future Ginnungagap offsite backup system.
The original VLAN 700 and point-to-point transit design will not be implemented.
The backup NAS is planned to run TrueNAS SCALE and support:
- ZFS snapshot replication for TrueNAS datasets.
- A suitable Proxmox backup replication mechanism, potentially involving a remote Proxmox Backup Server virtual machine.
Detailed implementation and validation are deferred.
Rationale
Section titled “Rationale”The primary requirement is secure, maintainable connectivity between designated backup endpoints.
A more elaborate routed network offered flexibility but also added cost and operational complexity beyond the current requirements.
Tailscale was selected because it better fits the project’s limited budget and intended scope.
Consequences
Section titled “Consequences”- VLAN 700 remains documented but is not deployed.
- The six existing operational VLANs are unchanged.
- The backup appliance can eventually use existing Internet infrastructure at the remote site.
- Future implementation must validate data security, access restrictions, backup integrity, connectivity, monitoring, and successful restoration.
- The project remains deferred until funding permits.
Architectural Lesson
Section titled “Architectural Lesson”A technically sophisticated solution is not necessarily the most appropriate solution.
Good architecture involves selecting the design that satisfies real requirements while balancing security, cost, complexity, maintainability, and operational risk.