Why?

​You have asked for it, so here it is...

USB Partition

The Wii U only allows you to format whole USB storage devices to use them for expanding the storage to store Wii U games. This stroopwafel plugin changes this. It lets you use a partition on your USB storage device for storing Wii U games. You can for example have one partition to use in vWii with USB Loaders and then a second Wii U formatted partition to store your Wii U games.

There are two variants of this plugin: the standard one (wafel_usb_partition.ipx) only mounts the Wii U formatted partition. The sd variant (wafel_usb_partition_sd.ipx) allow you to use a FAT32 partition as a SD card replacement.


If you want instead use a Partition on your SD card as USB storage for Wii U games look here: https://gbatemp.net/threads/sdusb-the-modern-way-to-play-wii-u-games-from-sd-at-full-speed.655744/

Prerequisites

​You need two things:

1. a way to launch minute (usually ISFShax)
2. a USB Storage device, like an external HDD, SSD or industrial USB Flash drive.

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.
If you want to use the SD emulation feature, you need to setup ISFShax to run completely from SLC (as you won't have a real SD card to load the files from)

For 2. you find already enough recommendations and people with strong optinions on what to use and what not, so I won't go into much detail there. Generally flash drives use the cheapest of the cheapest garbage flahs and therefore won't last long, even brand ones. So it's generally advised to avoid them or make sure it is really a good one by checking if it gives numbers for TBW and implements wear leveling.

Setup

​First of all make a Backup. If anything goes wrong, the whole Disk will be formatted and you lose everything* which was previously on it! You have been warned...

*testdisk might or might not be able to recover something if you are lucky, but do not rely on that.

Partitioning the USB disk​

On Windows you can probably use Disk Management with HDDS. If DIsk Management won't work for you or you have Pen drive you can use a third party tool like Minitool Partition Wizard or Easeus, on Linux you can use gparted.

The general rules are: The partition Table needs to be MBR, not GPT. The first Partition (by number, not physical location) is either ignored or used as SD card (depending on which favor of the plugin you use). If you want to use it as SD card, it needs to be primary (not logical) and formatted FAT32. From the other primary partitions only ones with the NTFS (or exFAT) type will be considered. The phsically last one of those will be chosen and used as (wfs) USB storage.

You can either chose from scratch by deleting all partitions and start from scratch or resize an existing partition to make room.
An example setup would be:
two primary partitions on the USB Disk:

1. FAT32 - (in gparted set lba flag). Here goes the vWii games and homebrew if you use the SD variant of the plugin.
2. NTFS - This partition will be seen by the Wii U as "USB", you use to store the Wii U games on (don't assign a drive letter)

NTFS won't be the file system the Wii U will be using, it is just there to tell the plugin which partition to use. The Wii U will later format it with it's own file system (wfs).

Installing the Plugin​

Get the latest wafel_usb_partition.ipx from here: https://github.com/StroopwafelCFW/wafel_usb_partition/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 usbpart.ipx

Using the Partition

​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. Before you start installing stuff on it, I would recommend you connect it back to the PC and check if it worked and the partitions are still there. After formatting the partition, you can also connect an existing USB storage and copy stuff over.

Caveats with the SD emulation

The SD emulation is only present in the Wii U OS. It won't have any affect on vWii and also isn't available in minute. So you can't use it to load the ios_plugins or do backups to in minute.
It should only be used without an actual SD inserted to avoid potential corruption. The Wii U FAT driver only supports one device. If two are connected the one which is detected later is used. If both are connected during bootup the USB one would win, since USB is detected later than the real SD.

 

[SDIO]

It sounds like you have a really old ISFShax install. I recommend you download the latest release and make sure to remove the old ios_plugins

 

[ukigh4ie2]

Using Aroma's Boot Selector to start directly into vWii, either System Menu or HBC, makes the FAT32 on the HDD invisible to the vWII. Booting regular into vWii from WiiU's System Menu works fine.

@SDIO, do you have any idea what could be causing this? Can you reproduce it?