OpenEmu, Dolphin and RetroArch: game libraries, save states and shader caches on a Mac
Emulators copy games into their own libraries and keep save states, shader caches and screenshots. Where each one keeps them, and what to clear first.
Emulators look small, and they are. What grows is everything around them: libraries of game files, sometimes copied rather than referenced, save states that capture the whole console's memory each time, shader caches, and screenshots.
Where each keeps its data
| Emulator | Folder | What grows |
|---|---|---|
| OpenEmu | ~/Library/Application Support/OpenEmu | Its game library (imported games are copied in by default), save states, screenshots |
| Dolphin | ~/Library/Application Support/Dolphin | Shader cache, save states, and game files if you keep them there |
| RetroArch | ~/Library/Application Support/RetroArch | Cores, thumbnails, save states, shader packs |
du -sh ~/Library/Application\ Support/{OpenEmu,Dolphin,RetroArch} 2>/dev/null
du -sh ~/Library/Application\ Support/OpenEmu/*/ 2>/dev/null | sort -hThe duplicate library
OpenEmu copies games into its own library by default when you import them. If you also kept the original folder of game files, you have everything twice. Its preferences let you turn copying off, so it reads games where they are. Check for the duplicate before buying more storage.
Save states
A save state stores the whole machine at that moment. For newer consoles each state can be large, and auto save states pile up. Remove old ones from inside each emulator, or sort the save state folder by date.
Shader caches
Dolphin and other emulators for 3D consoles build shader caches to reduce stutter. They are safe to delete and rebuilt as you play, at the cost of some stutter the first time.
Moving the library
Game files can live on an external drive. Point the emulator's library or game folder setting at it. See moving files to an external drive and, for games in general, Mac storage for gamers.
Common questions
Where does OpenEmu store games on a Mac?
In ~/Library/Application Support/OpenEmu. By default imported games are copied into its library, so the originals elsewhere are duplicates unless you turn copying off.
Can I delete the Dolphin shader cache?
Yes. It is rebuilt as you play. Games may stutter a little the first time until it is rebuilt.
Why are emulator save states so large?
Each save state captures the whole emulated machine's memory at that moment. Auto save states for newer consoles add up quickly.