Ctr-Gcs : DacoTaco Edition is a tool built to create or restore full, raw memory card backups and GCI save files just like the GC application Ctr-gcs did. These dumps can be saved to restore later or be used in emulators like Dolphin-emu. Unlike ctr-gcs however, this utility can read or write to unofficial memory cards; no matter what its size is.

The program will read & write the dump to the SD card (in the ctr-gcs folder) as card_dump.raw

Also please note that if you restore a corrupt dump to a memory card, or if the program shows an error while creating or restoring a dump, you may end up with a corrupted memory card.

http://wiibrew.org/wiki/Ctr-Gcs-DacoTaco-Edition