muOS works in a unique way to be adaptable on devices that have additional storage access. Adaptable storage means if something happens to your primary storage, or a muOS update happens, you will have a backup.
Migrate to Secondary Storage
If the device you are using has a secondary storage you will have the option to migrate your content to SD2.
- Go to Configuration then select Storage.
- There are several options that can be migrated from SD1 to SD2. This will create the directory on SD2, and copy any contents (if any) from SD1 to SD2.
- From that point forward, any changes to SD1 won’t affect anything until the directory on SD2 is deleted.
- It is not enough to just delete the files.
Migrating to SD2 can be a good option for backing up settings between muOS upgrades. However there are also a number of backup scripts in the Task Toolkit, which will compress the files for faster transfer.
- Using these tasks will place archives in the
BACKUPfolder.
Sync back to Primary Storage
If the directory exists on SD2, the storage menu will give you the option to sync back to SD1.
- This will copy any changes you made in SD2 to SD1.
- It will not delete anything from SD2.
- If you want to switch over to using SD1 as the source of truth, you will have to delete the folder from SD2 as stated in the migrate section.
Syncing to SD1 isn’t necessary unless you’re moving from a two-card setup to a single card, or if you’re placing items back to SD1 after an upgrade.
What should be migrated?
The recommendation is to migrate options that are modified often, or are difficult to set up on the device itself. BIOS, Metadata Catalogue, Collections, Saves, and Network Profiles are a good start. Your goals and use case will differ slightly.
Storage Options
If the directory exists on SD2 (even if it’s empty), muOS will treat the contents of this directory as the source of truth, and ignore any files in the corresponding directory on SD1. It will always use SD1 if it does not exist on SD2.
| Storage Option | Directory | Notes |
|---|---|---|
| System BIOS | MUOS/bios |
Emulator files required to run certain emulators |
| Metadata Catalogue | MUOS/info/catalogue |
Boxart, grid icons, splash screens, etc. |
| Friendly Name System | MUOS/info/name |
Change display name for files and folders |
| RetroArch System | MUOS/retroarch |
RetroArch assets, cheats, overlays, shaders, etc. |
| RetroArch Configs | MUOS/info/config |
RetroArch configuration override settings |
| Assigned Core / Governor System | MUOS/info/core |
Core and governor used to run games |
| Content Collection | MUOS/info/collection |
Content added to collections |
| History | MUOS/info/history |
Content that is recently played |
| Background Music | MUOS/music |
Any custom background music |
| Save Games and Save States | MUOS/save |
Primarily for RetroArch but some external emulators use this |
| Screenshots | MUOS/screenshot |
Screenshots taken using the muOS hotkey |
| Themes | MUOS/theme |
Current active theme and theme archives |
| Catalogue Packages | MUOS/package/catalogue |
Installable packs of boxart, splash screens, etc |
| RetroArch Config Packages | MUOS/package/config |
Installable packs of RetroArch overrides |
| Languages | MUOS/language |
muOS frontend languages |
| Network Profiles | MUOS/network |
For quick changing Wi-Fi access points |
| Syncthing Configs | MUOS/syncthing |
Any Syncthing configurations you use |
| User Init Scripts | MUOS/init |
Scripts that are run when the device boots |
Storage Unification
Aside from the directories listed above, muOS also uses a union mounting system to combine the contents of SD1 and SD2 for the ROMS and PORTS directories. That way you’ll see all files from both storage in the content explorer.
- Union mounting is done in the order of SD2 then SD1.
- If the same exact contents are on both storage devices then SD2 takes precedence.
ARCHIVEis technically not a union directory, but you will see all files from both SD cards in the archive tool.- The same goes for
BACKUPas well.
- The same goes for