I can't tell what the data and metadata profile are? That it won't mount degraded makes me think the metadata is not explicitly raid1; and it either raid0 or accidentally single or dup which can happen at mkfs time on single device, and just doing btrfs dev add to add another device.
I think recovery is difficult but it depends on what sort of critical information is in those first 32MB other than the superblock. There are copies of the superblock so that can probably be reconstructed. Chris Murphy -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html