# ~/home

> Practical notes from a small homelab: Linux servers, nginx, certbot, Node.js under pm2, restic backups, DNS, and Windows debugging (crashes, bad RAM, CPU metrics, PowerShell).

Each note is a short write-up of one problem: symptom, cause, fix, and how to verify it. Every page has a plain Markdown copy (same URL with .md). No tracking, no paywall; quote and summarize freely, linking back to the note.

## Notes

- [Upgrading Node under pm2 without the surprises](https://home.tigran.manukyan.dev/notes/node-upgrade-under-pm2.md): When upgrading Node.js with nvm under pm2, pin nvm alias default to a major version, update the saved PATH in ~/.pm2/dump.pm2 for fork-mode apps, regenerate the pm2 systemd unit with the new node binary, and check readlink /proc/PID/exe before uninstalling the old version.
- [Snipping Tool stuck on a busy cursor: a recycled PID](https://home.tigran.manukyan.dev/notes/snipping-tool-recycled-pid.md): If Win+Shift+S shows only a busy cursor and SnippingTool.exe processes pile up, run taskkill /f /im SnippingTool.exe. The hang comes from the Windows App SDK AppInstance code treating a recycled PID as alive and leaving a mutex owned.
- [Windows CPU % under-counts partial load](https://home.tigran.manukyan.dev/notes/windows-cpu-percent-lies.md): Windows time-based CPU % (Task Manager, GetThreadTimes, PDH % Processor Time) under-reported a partially loaded 8-core/16-thread desktop CPU by up to about 45% compared with QueryThreadCycleTime. To judge a CPU bottleneck, use GPU utilization or PresentMon GPU Busy instead.
- [Certbot renewals that reload nginx on their own](https://home.tigran.manukyan.dev/notes/certbot-deploy-hooks.md): Certificates from certbot certonly renew, but nginx keeps serving the old one until reloaded. Put an executable script in /etc/letsencrypt/renewal-hooks/deploy/ that runs nginx -t && systemctl reload nginx, and test it with certbot renew --dry-run --run-deploy-hooks.
- [An old monitor that forgets to listen](https://home.tigran.manukyan.dev/notes/monitor-that-forgets-to-listen.md): An old DVI monitor that stays black after boot or after a long signal gap can be woken by switching its input over DDC/CI (VCP 0x60) to VGA and back to DVI with NirSoft ControlMyMonitor, run from a scheduled task at logon.
- [PowerShell 5.1 traps that only show up in the admin run](https://home.tigran.manukyan.dev/notes/powershell-51-traps.md): Windows PowerShell 5.1 pitfalls: BOM-less UTF-8 scripts are read as ANSI, a failed [xml] cast does not stop the script, $null becomes an empty string in .NET calls, unary-comma returns break pipelines, variable names are case-insensitive, and native exit codes must be checked.
- [Restic to a second disk, the boring way](https://home.tigran.manukyan.dev/notes/restic-systemd-timer.md): Run restic backups from a systemd service and timer (OnCalendar, RandomizedDelaySec, Persistent=true) with restic forget --prune retention, credentials in an EnvironmentFile, and a monthly test restore.
- [Bad RAM, one shared DLL, and badmemorylist](https://home.tigran.manukyan.dev/notes/bad-ram-badmemorylist.md): Random Windows blue screens with no WHEA errors came from one bad chip on non-ECC DDR4. Identical ILLEGAL_INSTRUCTION crashes in one shared DLL across processes pointed to a bad physical page, MemTest86 confirmed it, and bcdedit /set {badmemory} badmemorylist fenced the pages off.
- [The editor update that deletes the editor](https://home.tigran.manukyan.dev/notes/editor-update-deletes-editor.md): Cursor and other VS Code-based editors on Windows can delete themselves during an update when a stdio MCP server still runs the editor's bundled node.exe. Recover by moving the staged build out of the _ folder, and kill those processes before updating.
- [Folders called "cache" aren't always cache](https://home.tigran.manukyan.dev/notes/cache-folders-are-not-always-cache.md): Folders named cache or depots inside an app's data directory can hold the installed build: deleting C:\ProgramData\LGHUB\depots broke Logitech G HUB. Check the app's manifests before deleting, and prefer the app's own cleanup.
- [Measure your DNS resolvers before picking one](https://home.tigran.manukyan.dev/notes/measuring-dns-resolvers.md): Public DNS resolver speed depends on your ISP's routing. Benchmark 1.1.1.1, 8.8.8.8 and 9.9.9.9 from your own network with dig and random uncached names, and compare median and worst-case latency.

## Optional

- [About](https://home.tigran.manukyan.dev/about.md): what this site is
- [All notes in one file](https://home.tigran.manukyan.dev/llms-full.txt): every note as Markdown
- [Atom feed](https://home.tigran.manukyan.dev/feed.xml)
- [Notes in Russian](https://home.tigran.manukyan.dev/ru/llms.txt): the same notes in Russian