SD Filesystem

Overview

sd
└── Nintendo
    ├── Album
    ├── Contents
    └── save

All files stored under the Contents sub-directories and save/ use the NAX0 format.

Album

Contains the screenshots: "YYYY/MM/DD/<hex>.jpg". These contain some sort of MAC, the system will display an error for screenshots with invalid MACs.

save

Contains system-only savedata "8000000000000000" and "8000000000000124".

8000000000000000 is a FS module save describing the other system savedata on the SD card (normally only 8000000000000124).

8000000000000124 is the NCM module save describing what contents are installed to the SD card.

Contents

It seems this directory didn't exist until 2.0.0.

Contains directories "placehld" and "registered".

Also contains file "private", which stores the 0x10 #SetSdCardEncryptionSeed|sd card seed verification vector.

placehld and registered

"placehld" and "registered" store game contents; contents are initially downloaded temporarily into the "placehld" folder, and then moved into the registered folder when downloading is complete.

Some of the "placehld/<hex>" directories are temp-only and don't get moved into "registered".

No titleIDs are stored in any directories/filenames here.

All hex IDs(below 000000XX and NcaId) used here are unique per title/content. XX is calculated as the first byte from the output of SHA-256(NcaId).

Game contents are stored inside NAX0 archives; due to the 4 GB filesize limit on FAT32, contents that are bigger than 4 GB have additional file contents automatically split into separate files. This automatic file-splitting occurs even on exFAT SD cards where it is not necessary.

<sub-directory under Contents>
└── <directories with upper-case hex: 000000XX>
    └── <lowercase hex NcaId>.nca
        └── 00 actual file for data storage
        └── 01 (storage for file data at +4GB in the actual NCA)
        └── {etc}