WFS

WFS is the name of the filesystem stored on the Wii U's eMMC, as well as on USB storage devices CafeOS/IOSU formats. Despite serving (in part) a similar purpose to SFFS, it is an entirely different (and much more complex) format.

Caveats

When reading a WFS filesystem from the eMMC, it is important to also apply updates from the SCFM first, else you will get stale data. Many WFS dumping/extracting utilities do not do this. NPLL's WFS driver does.

Compatibility

While NPLL supports reading files from WFS, neither Wii-Linux, nor linux-wiiu, nor NetBSD can do so.