wiki: add 4 new articles from archive, merge 8 archive notes into existing articles (73 articles)

New: mdadm RAID rebuild, Mastodon instance tuning, Ventoy, Fedora networking/kernel recovery.
Merged: Glacier Deep Archive into rsync, SpamAssassin into hardening checklist,
OBS captions/VLC capture into OBS setup, yt-dlp subtitles/temp fix into yt-dlp.
Updated index.md, README.md, SUMMARY.md with 21 previously missing articles.
Fixed merge conflict in index.md Recently Updated table.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

02-selfhosting/services/mastodon-instance-tuning.md

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+---
+title: "Mastodon Instance Tuning"
+domain: selfhosting
+category: services
+tags: [mastodon, fediverse, self-hosting, majortoot, docker]
+status: published
+created: 2026-04-02
+updated: 2026-04-02
+---
+
+# Mastodon Instance Tuning
+
+Running your own Mastodon instance means you control the rules — including limits the upstream project imposes by default. These are the tweaks applied to **majortoot** (MajorsHouse's Mastodon instance).
+
+## Increase Character Limit
+
+Mastodon's default 500-character post limit is low for longer-form thoughts. You can raise it, but it requires modifying the source — there's no config toggle.
+
+The process depends on your deployment method (Docker vs bare metal) and Mastodon version. The community-maintained guide covers the approaches:
+
+- [How to increase the max number of characters of a post](https://qa.mastoadmin.social/questions/10010000000000011/how-do-i-increase-the-max-number-of-characters-of-a-post)
+
+**Key points:**
+- The limit is enforced in both the backend (Ruby) and frontend (React). Both must be changed or the UI will reject posts the API would accept.
+- After changing, you need to rebuild assets and restart services.
+- Other instances will still display the full post — the character limit is per-instance, not a federation constraint.
+- Some Mastodon forks (Glitch, Hometown) expose this as a config option without source patches.
+
+## Media Cache Management
+
+Federated content (avatars, headers, media from remote posts) gets cached locally. On a small instance this grows slowly, but over months it adds up — especially if you follow active accounts on large instances.
+
+Reference: [Fedicache — Understanding Mastodon's media cache](https://notes.neatnik.net/2024/08/fedicache)
+
+**Clean up cached remote media:**
+
+```bash
+# Preview what would be removed (older than 7 days)
+tootctl media remove --days 7 --dry-run
+
+# Actually remove it
+tootctl media remove --days 7
+
+# For Docker deployments
+docker exec mastodon-web tootctl media remove --days 7
+```
+
+**Automate with cron or systemd timer:**
+
+```bash
+# Weekly cache cleanup — crontab
+0 3 * * 0 docker exec mastodon-web tootctl media remove --days 7
+```
+
+**What gets removed:** Only cached copies of remote media. Local uploads (your posts, your users' posts) are never touched. Remote media will be re-fetched on demand if someone views the post again.
+
+**Storage impact:** On a single-user instance, remote media cache can still reach several GB over a few months of active federation. Regular cleanup keeps disk usage predictable.
+
+## Gotchas & Notes
+
+- **Character limit changes break on upgrades.** Any source patch gets overwritten when you pull a new Mastodon release. Track your changes and reapply after updates.
+- **`tootctl` is your admin CLI.** It handles media cleanup, user management, federation diagnostics, and more. Run `tootctl --help` for the full list.
+- **Monitor disk usage.** Even with cache cleanup, the PostgreSQL database and local media uploads grow over time. Keep an eye on it.
+
+## See Also
+
+- [[self-hosting-starter-guide]]
+- [[docker-healthchecks]]