Oznog

An automatic transfer switch, or ATS, is a device with two power inputs and one output.

The trap here is how convincingly the symptom mimics an unrelated class of problem.

Backup verification tends to stop one step short of the thing anyone actually cares about.

A renumbering left an administrative login page answering on a public address for most of a day.

A small, concrete fact for anyone running rack PDUs with internal branch fuses.

A firewall’s own login page ended up reachable from anywhere on the internet on 20260820, for a time nobody recorded, and was closed about ten minutes after it was noticed, as the fallout of an otherwise routine address renumber.

A rack PDU has a field for the name of the supply feeding it.

Backrest’s operations API returns at most 21 error entries per run.

DNS secondaries are supposed to be a solved, boring problem.

A backup exclude list is not really a list of paths.

Many long-running daemons read their configuration once at startup and never again.

A capacity check that correctly identifies a coming failure is only useful if something actually stops when it fires.

The access point’s most famous default-configuration trap, a DHCP server that would fight the real one, was anticipated correctly.

Buying used enterprise network gear carries the same risk as buying used enterprise servers.

A firewall failover is supposed to be invisible to everyone outside the building.

This is a design correction rather than an incident, and it is here because it changed a real decision on 20260817, before that decision became expensive to reverse: a long high-speed cable run between racks that the existing plant could not support anywa…

Setting up redundant DHCP sounds like flipping one switch.

A pair of firewalls that are supposed to fail over into each other instead both decided they were in charge at once.

Both failures are worth understanding mechanically, because both are easy to reproduce anywhere.

A closure is the complete set of store paths a NixOS system depends on, so its hash is a fingerprint of the whole machine’s declared state.

Anyone building a fleet operated by several automated actors hits this question in the first week.

The generalisation arrives immediately.

An appliance NAS keeps its entire personality, network configuration, container definitions, user accounts and host keys, on a small internal USB flash drive separate from the data disks.

Two tools that both call themselves “delete” can mean opposite things.

A batch file-deletion tool’s list format borrowed a very old Unix convention.

Two mistakes in one script arrived at the same destination, an alarm system nobody could trust, from opposite directions.

Backup systems built to resist deletion, an append-only mode so that a compromised client cannot erase history, create a failure mode that looks nothing like what it is.

Cloud object storage services often expose version retention as a small handful of named presets, and the names can be actively misleading about what security property each one provides.

A container platform with a size-capped storage backend fails in a particularly confusing way.

An appliance-style NAS operating system such as Unraid runs its entire root filesystem in RAM by design, which is normally invisible.

Self-hosted media tools that promise not to duplicate your library often do exactly what they say.

An AI agent working through a large file-reorganisation project destroyed three of Christoph’s voicemail recordings in a single command.

The hardware that waited isn’t waiting anymore.

Node0 is operational.

Every post in this series mentions collaboration with Claude.

Twenty-two months from hardware purchase to operational fleet.

Four DI servers.

The utility tier was up.

di03 and di04 proved the patterns.

Not every workload needs a Threadripper.

The storage foundation was in place.

The mental shift to config as code on the Framework was practice.

December 31, 2025.

December 27 through 30, 2025.

After months of the hardware waiting, it was finally time to build.

Christmas morning.

A month into the Framework 13 experiment.

Two days into the Framework 13 setup, something clicked.

The hardware had waited for months.

This post is dated March 2024-when the hardware was purchased.