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".

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}