[Btrfs-devel] BTRFS partition usage...

[David Miller]

Filesystems like ext2 put their superblock 1 block into the partition
in order to avoid overwriting disk labels and other uglies.  UFS does
this too, as do several others.  One of the few exceptions I've been
able to find is XFS.

This is a real issue on sparc where the default sun disk labels
created use an initial partition where block zero aliases the disk
label.  It took me a few iterations before I figured out why every
btrfs make would zero out my disk label :-/