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6d81e7f020
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>
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title, domain, category, tags, status, created, updated
| title | domain | category | tags | status | created | updated | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Mastodon Instance Tuning | selfhosting | services |
|
published | 2026-04-02 | 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:
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
Clean up cached remote media:
# 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:
# 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.
tootctlis your admin CLI. It handles media cleanup, user management, federation diagnostics, and more. Runtootctl --helpfor 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.