Why Media Server to Media Server is fragile (and when it’s okay)
Backup first. Make a backup of each server’s database/app data before you sync (Plex, Jellyfin, Emby). Test you can restore it. If you can’t restore, don’t do two-way. Risks: lost/overwritten watched history, ratings, and lists if IDs shift.
Not actually the same library. Different folders, editions/cuts, partial seasons, extras, 4K vs 1080p. A “mirror” is a myth; things drift as soon as paths or editions differ.
ID mismatches = chaos. Plex GUIDs, Jellyfin/Emby IDs, TMDB/TVDB/IMDb remaps, season/episode offsets, specials vs. regular seasons. Small mismatch → big, silent mis-writes to the wrong item.
Cascade mistakes. One bad match on Server A copies to B; later rematch on A makes B look “wrong,” you “fix” B, then A flips back. Hello yo-yo.
