About

A small, deliberately slow notebook about storage engines, filesystems, and the parts of I/O that only show up in incident reviews.

Who

I have spent the better part of a decade on backend infrastructure, mostly on the boundary where a database stops trusting the operating system. Before that I wrote firmware for industrial data loggers, which is where the habit of distrusting durability claims comes from.

I am not going to put a résumé here. If a note is useful to you, that is the only credential that matters; if it is wrong, the credential does not help.

Why this exists

Every few years I rediscover the same handful of facts about write barriers, page cache behaviour, and background compaction, usually at an inconvenient hour. Writing them down in public forces me to be specific about which kernel, which filesystem, and which mount options a claim actually applies to.

A durability guarantee you cannot name the version number of is a guess with better posture.

Corrections

If something here is wrong, I would genuinely rather know. Write to notes@tgweb.cdn5.dev. I read everything and reply to most of it, eventually.

Notes get edited in place when they are wrong. Substantive changes are listed at the bottom of the note itself rather than in a separate changelog, because I have never once read someone else's changelog.