It pays to back up your games, saves, and anything you don't want to lose.
I just moved, and I lost my Wii's SD card in the shuffle, so I was using my DSi's SD card with all of my games on it to load apps in the HBC. I just moved all my DSi data to a folder on the SD called DSi, then I moved my Wii SD card's backup onto it.
I then later went and placed a wad file on the SD card, when I went to put it in my Wii and load the HBC, nothing happened.
I went back and put the SD card into my computer, and somehow when I copied the wad file onto the SD card, it deleted everything else but that.
Thank God I had backed up my entire DS SD card a few days ago.
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So, just as a reminder to everyone, if you haven't yet backed up your SD cards, or haven't done it in a while, it'll be a life-saver if the unexpected happens.
I just moved, and I lost my Wii's SD card in the shuffle, so I was using my DSi's SD card with all of my games on it to load apps in the HBC. I just moved all my DSi data to a folder on the SD called DSi, then I moved my Wii SD card's backup onto it.
I then later went and placed a wad file on the SD card, when I went to put it in my Wii and load the HBC, nothing happened.
I went back and put the SD card into my computer, and somehow when I copied the wad file onto the SD card, it deleted everything else but that.
Thank God I had backed up my entire DS SD card a few days ago.
------
So, just as a reminder to everyone, if you haven't yet backed up your SD cards, or haven't done it in a while, it'll be a life-saver if the unexpected happens.