btrfs-map-logical <options> <device>
btrfs-map-logical can be used to find out what the physical offsets are on the mirrors, the result is dumped to stdout by default.
Mainly used for debug purpose.
-l|--logical <logical_num>
-c|--copy <copy>
-o|--output <filename>
-b|--bytes <bytes>
btrfs-map-logical will return 0 if no error happened. If any problems happened, 1 will be returned.
mkfs.btrfs(8)