In the wii u s case it means you re going to need to purchase a y cable plug the single end into the external and both of the other ends into the two usb ports on the wii u.
External hard drive with power supply for wii u.
That should see you through the next eshop sale.
Your other option is to use a portable external hard drive which normally gets power through its usb cable rather than an ac adapter.
At this price you get the biggest hard drive the wii u can still use plus it has an external power supply.
Portable external hard drives.
Due to the wide range of external storage devices usability and performance will vary.
For best results we recommend using a external storage device with its own power supply that connects to the wii u system via the usb port on the console.
Fortunately the wii u supports external hard drives so even if you ve got the standard with its itty bitty 8gb drive you can add up 2tb of space.