BTRFS raid is usage-aware, so a rebuild will not need to do a bit-for-bit copy of the entire disk, but only the parts that are actually in use. Also, because bt

BTRFS raid is usage-aware, so a rebuild will not need to do a bit-for-bit copy of the entire disk, but only the parts that are actually in use. Also, because btrfs has data checksumming, it can detect read errors even when the disk reports a successful read (however, it will not verify the checksum during regular operation, only during scrub).