> There is no encryption to my knowledge (not an expert in mdadm). linux md doesn't do encryption. But there are other things, like dm-crypt, that it can be combined with to do encryption. That doesn't look like a superblock, that looks like random bits, as produced by encryption or good compression. (Could be jpeg, mp3, or compressed video, it's hard to tell.) *And* the first few backup superblocks appear to be trashed as well. This means either at least a gigabyte of data got overwritten, or some kind of underlying transformation got changed, so the superblocks aren't visible in the right places any more. The obvious possibilities are: 1) Data scrambling, such as from encryption. 2) Address scrambling, such as by moving the components in a RAID aroud or assembling with a different stripe size. If you can find anywhere a sector that looks like a superblock as described at https://ext4.wiki.kernel.org/index.php/Ext4_Disk_Layout#The_Super_Block we can try to figure out what's going on. They're supposed to be located at blocks 32768 * 3**k, 32768 * 5**k, and 32768 * 7**k, for k = 0, 1, 2, .... That is, 32768 times 1, 3, 9, 27, 81, 243, ...; 32768 times 1, 5, 25, 125, 625, ...; and 32768 times 1, 7, 49, 343, ... (Those are 4K blocks; myltiply by 8 for 512-byte sector numbers.) While the primary superblock contains file system statistics and flags, the backups are generally never written after file system creation time, so it's *really* hard to understand how they could have been overwritten by any sort of normal file system activity. Let's see... you have 1952211968K in your RAID, meaning 488052992 4K blocks, and 14895 block groups. The *last* backup superblocks should be at 3^8 = 6561, 5^5 = 3125, and 7^4 = 2401. Try the following: dumpe2fs -h -o superblock=$((32768*3**8)) /dev/md0 dumpe2fs -h -o superblock=$((32768*5**5)) /dev/md0 dumpe2fs -h -o superblock=$((32768*7**4)) /dev/md0 dumpe2fs -h -o superblock=$((32768*3**7)) /dev/md0 If none of those work, either something overwrote *most* of your drive, or something has happened to give that illusion. As Ted says, I'd research option 2 very carefully. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
