Why?

​Even though the Wii U has a built in SD slot, it doesn't support using it as a storage expansion to store Wii U games (unlike it's predecessor). USB pen drives are notoriously unreliable and hard drives are bulky and require extra power or a Y cable, using up multiple ports. Today big reliable SD cards have become cheap. Since a SD is needed anyway for homebrew, it would be nice to use that too as storage for games.
There have been solutions in the past like Loadiine, but this had various problems, the biggest of them performance and is not longer supported by current homebrew environments (Aroma).

SDUSB

​SDUSB solves these problems. It uses a second partition on the SD card, which will be formatted to the Wii Us native file system and therefore run at full speed. The partition will show up as a USB device and can therefore be managed using the built in Data Management in the system settings. SaveMii, WUP Installers etc. all work with this, like it is a USB storage device. Also HAI (VC Wii Titles) work with SDUSB.
SDUSB does all that by patching IOSU (the OS that runs on the ARM processor). It is implemented as a stroopwafel plugin.

If you instead want to partition your USB HDD to use it for Wii U games and other stuff look here: https://gbatemp.net/threads/usb-partition-use-partitioned-usb-hdds-with-the-wii-u.656209/

Prerequisites

​You need two things:

1. a way to launch minute
2. a reliable SD card

For 1. the recommended way is to setup ISFShax, for that we have a guide here: How to set up ISFShax
If you don't want to commit to installing ISFShax yet you can skip the "Installing ISFShax" step in the ISFShax setup guide and instead run it manually through the chosen exploit on every reboot.
Instead if ISFShax you can also use defuse, in case you have that already.

For 2. It is highly recommended that you use an Endurance branded SD card from a reputable brand. Since your save games will also be saved there, you rather want to spend $5 more then to lose all your save games because your cheapo sd card died. Also be aware of fakes, even on Amazon you can get fake SD cards...
The speed of the SD card isn't too important, as the Wii U is limited to 25MB/s (same as the internal memory) anyway. Every somewhat recent SD card should be able to get that speed. Choose Reliability > Access Time > Throughput.

Setup

​

Partitioning the SD card​

On Windows you need to use a third party tool like Minitool Partition Wizard or Easeus, on Linux you can use gparted.
You need to have two primary partitions on the card:

1. FAT32 - (in gparted set lba flag). This is what the PC will see and all your homebrew goes (you should already have this)
2. NTFS - This partition will be the "USB", you use to store the Wii U games on (don't assign a drive letter)

Shrink the existing FAT32 partition to make room and then create the primary NTFS partition after it. It's recommended to align the Partitions on 64MiB boundaries and use a multiple of 64MiB for the size. NTFS won't be the file system the Wii U will be using, it is just there to tell SDUSB which partition to use (it will pick the first NTFS one). The Wii U will later format it with it's own file system.

​

Installing the Plugin​

Get the latest wafel_sd_usb.ipx from here: https://github.com/jan-hofmeier/wafel_sd_usb/releases and place it in your ios_plugins folder. That is either wiiu/ios_plugins on the SD card or /sys/hax/ios_plugins on the slc. For slc you have to rename it to something shorter like sdusb.ipx

Using SDUSB

​If you now boot boot back up, the Partition shows up as a USB device, which needs to be formatted and can then be used as usual. After formatting the SDUSB, you can also connect an existing USB storage and copy stuff over.

Known Problems

​

• GC VC Injectes don't work when installed to the SDUSB (they still work from Internal Memory)

 

[4d1xlaan]

would be nice tbh if you could just browse files directly without having to ftp in. I have to change my router settings every time to make it temporarily compatible with the wii u

weird how ds, wii, 3ds, switch all have homebrew to directly browse and interact with the filesystem, but on wii u everyone just accepts the ftp status quo

 

[V10lator]

@4d1xlaan There where attempts of writing file managers years ago but these failed horribly as the filesystem I/O API of the homebrew SDK wasn't stable back then, causing bugs everywhere.

Today it seems no developer cares enough as they are all used to use FTP since years.

 

[Hedoking]

This might be a stupid question, but will I still be able to browse the content of the FAT32 partitions normally? I don't want to have to ftp every time I want to add something to my install folder.

 

[SDIO]

You mean from the PC? Yes that works as usual for the fat32 partition

 

[greator]

You said "a way to launch minute".
So I still need to install minute along with ISFShax?

 

[SDIO]

minute is just the fw.img file you put on the SD. The ISFShax guide shows how to get it.

EDIT: moved the other text to the correct thread

 

[Ruugosus]

Thank you SDIO for the amazing program! You guys have been killing it with the Wii U homebrew scene as of late!

Not sure if this happened to anyone else, but when I had the Wii U format my partitioned SD card, it chose the FAT32 partition instead of the NTFS one. Nothing detrimental happened; the boot files for ISFShax were in the SLC and I formatted the NTFS partition to FAT32 and put my backed up SD card files in there.

Everything's functioning as expected, but that definitely caught me off guard lol

 

[SDIO]

can you show how your SD is partitioned?

 

[Ruugosus]

can you show how your SD is partitioned?

Sure! Here's what it looks like on MiniTool Partition now:

 

[SDIO]

can you show how it looks in windows disk management? I need to know which partition it sees at 0 and which as 1.
Also with which did you format the FAT32 partition when you created it?
Can you send me the MBR (first 512bytes of the disk)?

 

[tmnr1992]

Sure! Here's what it looks like on MiniTool Partition now:

View attachment 440172

According to the guide:
NTFS - This partition will be the "USB", you use to store the Wii U games on (don't assign a drive letter).

Try setting the drive letter to none on your second partition, that worked for my HDD.

 

[Ruugosus]

can you show how it looks in windows disk management? I need to know which partition it sees at 0 and which as 1.
Also with which did you format the FAT32 partition when you created it?
Can you send me the MBR (first 512bytes of the disk)?

Here's how it looks on Windows disk management. Originally, the partition on the left was my NTFS, while the right was my FAT32 (originally was exFAT when fresh, changed it to FAT32 and adjusted the size. Then I made the remaining unallocated space on the left NTFS:

And here's what I think you were looking for in regards to the MBR?:

Spoiler

According to the guide:
NTFS - This partition will be the "USB", you use to store the Wii U games on (don't assign a drive letter).

Try setting the drive letter to none on your second partition, that worked for my HDD.

Hmm, when I did this step, I saw that formatting it to NTFS gave it a letter, and I think I did another step to remove the assigned letter for that partition. I'm not 100% sure now, unfortunately.

 

[SDIO]

I think I understand what happened. You had the first partition as NTFS. SDUSB ignores the first partition and only looks at the other partitions. Then the second partition was originally exFAT, which has the same ID as NTFS and when you formatted it to FAT32, the partition type probably wasn't changed.

Also what you showed in the hex editor there is the PBR (the first sector of the Partition, not the SD)

 

[Ruugosus]

Gotcha, that makes sense now. Thanks for clearing that up! And darn, thought I figured out how to find the MBR lol