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>
- Logical extent to map.
- -c|--copy <copy>
- Copy of the extent to read(usually 1 or 2).
- -o|--output <filename>
- Output file to hold the extent.
- -b|--bytes <bytes>
- Number of bytes to read.
btrfs-map-logical will return 0 if no error happened. If any problems happened, 1 will be returned.