I followed a YouTube video a long time ago, he thought it was necessary to start from zero so I lost the installed games, i only save the gamesave of Pokemon shuffle because it was the only one worth it, at first I tried to do a backup of my SD, but it was corrupted along with Pokemon shuffle, when I installed a9lh, my SD got corrupted right before the ctr transfer, so I copied the necessary archives, even I change the adapter and the SD I experience corruption problems, the funny thing was when I copy my SD backup I realized it was an older copy, so I transfer 20 gigas again, I never had these problems with hdd or USB sticks about the corruption problems, it wasn't cfw related but a bit annoyed, when I modded a friend's 3ds I didn't experience any problem even with the same sd and the same adapter, I have some write issues with it though, so right now I do wireless transfer, I have a o3ds