ADR 0006: A low-power mini-PC Proxmox cluster for PROD
Three ThinkCentre Tiny machines in a cluster, with local ZFS and replication, within an energy budget of €40 a month.
Superseded decision. This decision was superseded by ADR 0010 on 26/09/2026. It is kept for the record.
Context
The 24/7 services need high availability, with a strong constraint: at most €40 of electricity a month for the whole infrastructure, i.e. about 280 W of continuous average draw.
Options considered
- 3 × ThinkCentre Tiny (M720q / M920q): ~10 W per node at idle, low second-hand cost.
- 3 × Minisforum MS-01: built-in 10 Gb, much more RAM, but ~30 W per node and a high purchase cost.
- 2 nodes + QDevice: cheaper, but less headroom when something fails.
Decision
Three ThinkCentre Tiny machines. VM storage on local ZFS with Proxmox replication and HA; Ceph postponed until 10 Gb networking and SSDs with power-loss protection arrive.
Consequences
- Infrastructure estimated at €20 to €28 a month, with the LAB server powered on only on demand.
- Asynchronous replication: at worst a few minutes of data lost if a node fails.
- Power draw measured through the UPS (NUT) and tracked as a PDCA indicator.