2025 in review: the measurement year

Looking back, 2025 was the year of measuring things I had previously guessed at: CPU governors, DNS latency, appliance power, drive health. None of the experiments were hard; all of them changed a decision.

Decisions the data changed

schedutil replaced performance as the default governor on every box, worth a few watts per machine. DNS resolvers got re-ranked by p95 instead of median, which flipped my choice. The freezer got an early-warning rule after the fingerprint classifier went live.

Writing

Eighteen posts, and for the first time every one of them had a number or a procedure in it. The archive is starting to look like an operations manual written by someone who lives here.

2026 plan, stated publicly so it can be checked: fewer new toys, more verification. The queue is already just one item deep, which feels right.