https://vein.urikrait.online/Short notes on latency, links and small self-hosted systems. https://vein.urikrait.online/posts/why-i-still-read-man-pages.htmlhttps://vein.urikrait.online/posts/why-i-still-read-man-pages.htmlSun, 01 Nov 2026 09:00:00 +0000Search results answer the question you typed. A man page answers the question you should have asked. Reading the whole entry for a tool I use daily almost always turns up a flag that replaces a small script I wrote years ago. https://vein.urikrait.online/posts/leave-headroom.htmlhttps://vein.urikrait.online/posts/leave-headroom.htmlSat, 31 Oct 2026 09:00:00 +0000Running a machine at ninety percent memory or CPU looks efficient on a graph. In practice it means there is no room for the burst that always comes, and the burst then turns into swapping, timeouts and restarts. https://vein.urikrait.online/posts/a-small-server-s-memory.htmlhttps://vein.urikrait.online/posts/a-small-server-s-memory.htmlFri, 30 Oct 2026 09:00:00 +0000On a machine with little memory, every resident process counts. Language runtimes, idle workers and generous caches add up quickly, and the page cache, which keeps the system responsive, is what gets squeezed first. https://vein.urikrait.online/posts/swap-is-not-a-dirty-word.htmlhttps://vein.urikrait.online/posts/swap-is-not-a-dirty-word.htmlThu, 29 Oct 2026 09:00:00 +0000People disable swap on small servers to keep things snappy, then wonder why the kernel kills a process when memory gets tight. A little swap gives the kernel somewhere to put pages that are never touched again. https://vein.urikrait.online/posts/what-uptime-really-measures.htmlhttps://vein.urikrait.online/posts/what-uptime-really-measures.htmlWed, 28 Oct 2026 09:00:00 +0000A server with five hundred days of uptime is often admired, but it also means five hundred days without a kernel update and without proof that it boots cleanly. https://vein.urikrait.online/posts/quiet-hours.htmlhttps://vein.urikrait.online/posts/quiet-hours.htmlMon, 26 Oct 2026 09:00:00 +0000Scheduling heavy jobs for the middle of the night made sense when everyone shared one time zone. Today "quiet" depends on where the users are, and the quietest hour may be in the middle of someone's afternoon. https://vein.urikrait.online/posts/notes-on-file-permissions.htmlhttps://vein.urikrait.online/posts/notes-on-file-permissions.htmlSun, 25 Oct 2026 09:00:00 +0000The simplest permission model is still the most useful one: each service runs as its own user and owns only the files it needs. Everything else is readable at most, and secrets are readable only by their owner. https://vein.urikrait.online/posts/the-paper-notebook.htmlhttps://vein.urikrait.online/posts/the-paper-notebook.htmlSat, 24 Oct 2026 09:00:00 +0000For all the tools available, a paper notebook remains my favourite debugging aid. Writing down each hypothesis and its result slows me down just enough to think, and it leaves a record when the problem returns. https://vein.urikrait.online/posts/recovering-from-a-full-inode-table.htmlhttps://vein.urikrait.online/posts/recovering-from-a-full-inode-table.htmlFri, 23 Oct 2026 09:00:00 +0000A disk can be full even when plenty of space is free, because every file needs an entry in a fixed-size table. Millions of tiny files, often from a runaway cache or mail queue, can exhaust it. https://vein.urikrait.online/posts/bandwidth-is-not-speed.htmlhttps://vein.urikrait.online/posts/bandwidth-is-not-speed.htmlThu, 22 Oct 2026 09:00:00 +0000A wider pipe lets more data through at once, but it does not make any single exchange arrive sooner. For loading a small web page, the round trip time usually matters more than the capacity of the link. https://vein.urikrait.online/posts/reboots-as-a-test.htmlhttps://vein.urikrait.online/posts/reboots-as-a-test.htmlWed, 21 Oct 2026 09:00:00 +0000A reboot tests more than people think: that services start in the right order, that mounts come back, that firewall rules are restored, that nothing depends on a command someone typed by hand months ago. https://vein.urikrait.online/posts/sorting-by-the-right-column.htmlhttps://vein.urikrait.online/posts/sorting-by-the-right-column.htmlTue, 20 Oct 2026 09:00:00 +0000A process list sorted by processor usage shows what is busy right now. Sorted by memory, it shows what is heavy. Sorted by start time, it shows what changed recently. https://vein.urikrait.online/posts/time-zones-in-calendars.htmlhttps://vein.urikrait.online/posts/time-zones-in-calendars.htmlSun, 18 Oct 2026 09:00:00 +0000Scheduling across time zones looks like simple arithmetic until a region changes its rules or daylight saving starts on different dates in different places. Storing a meeting as a moment in UTC loses the intent if the organiser's local rules change. https://vein.urikrait.online/posts/mtu-briefly.htmlhttps://vein.urikrait.online/posts/mtu-briefly.htmlSat, 17 Oct 2026 09:00:00 +0000The maximum transmission unit is the largest packet a link will carry in one piece. When something along the path has a smaller limit and the signal that would tell the sender gets lost, large packets disappear while small ones get through. https://vein.urikrait.online/posts/reading-a-traceroute.htmlhttps://vein.urikrait.online/posts/reading-a-traceroute.htmlFri, 16 Oct 2026 09:00:00 +0000Traceroute shows each hop on the way to a destination and how long it took to answer. The tempting mistake is to blame the first hop that shows a high number. https://vein.urikrait.online/posts/measuring-what-you-actually-feel.htmlhttps://vein.urikrait.online/posts/measuring-what-you-actually-feel.htmlTue, 14 Jul 2026 09:00:00 +0000Average throughput is the number everyone quotes and almost nobody experiences. What a person notices sitting in front of a screen is the tail: the ninety-ninth percentile of round-trip time, the stall while a buffer drains, the half second before the first byte. A link can be fast and still feel broken. https://vein.urikrait.online/posts/small-machines-fewer-moving-parts.htmlhttps://vein.urikrait.online/posts/small-machines-fewer-moving-parts.htmlSat, 02 May 2026 09:00:00 +0000A two-gigabyte virtual machine is enough to run more than people expect, provided the parts are boring. One process per job, plain files for configuration, logs that a human can read without a query language. Complexity is rented, not owned. https://vein.urikrait.online/posts/on-keeping-notes-in-public.htmlhttps://vein.urikrait.online/posts/on-keeping-notes-in-public.htmlSat, 21 Mar 2026 09:00:00 +0000Anything written for an audience of one gets sloppy. Publishing forces the second pass where the actual reasoning shows up — usually along with the mistake.