sudo make-bcache -C /dev/sda3 -B /dev/sdb1 --wipe-bcacheDevice /dev/sda3 already has a non-bcache superblock, remove it using wipefs and wipefs -a
Wiping up the partition would not work as bcache is already using it for something
sudo wipefs -a /dev/sda3
wipefs: error: /dev/sda3: probing initialization failed: Device or resource busy
Also detaching the device from bcache won't work, since the bcache0 is not really there yet.
echo eb99feda-fac7-43dc-b89d-18765e9febb6 > /sys/block/bcache0/bcache/detachSeems the solution was to stop the bcache instead:
cd /sys/block/bcache0 bash: cd: /sys/block/bcache0: No such file or directory
sudo sh -c "echo 1 > stop"