Unmount and create a new file system on your partition:
# umount /dev/sdb2
- # mkbtrfs -L GENTOO -m single -d single /dev/sdb2
+ # mkfs.btrfs -L GENTOO -m single -d single /dev/sdb2
Note that I've disabled raid for both the metadata and data to save
space. This will make it harder to recover from corruption, but the