Recently, my external hard drive enclosure failed (the hard drive itself powers up in another enclosure). However, as a result, it appears its EXT4 file system is corrupt.
The drive has a single partition and uses a GPT partition table (with the label ears
).
fdisk -l /dev/sdb
shows:
Device Boot Start End Blocks Id System
/dev/sdb1 1 1953525167 976762583+ ee GPT
testdisk
shows the partition is intact:
1 P MS Data 2049 1953524952 1953522904 [ears]
... but the partition fails to mount:
$ sudo mount /dev/sdb1 a
mount: you must specify the filesystem type
$ sudo mount -t ext4 /dev/sdb1 a
mount: wrong fs type, bad option, bad superblock on /dev/sdb1,
fsck
reports an invalid superblock:
$ sudo fsck.ext4 /dev/sdb1
e2fsck 1.42 (29-Nov-2011)
fsck.ext4: Superblock invalid, trying backup blocks...
fsck.ext4: Bad magic number in super-block while trying to open /dev/sdb1
and e2fsck
reports a similar error:
$ sudo e2fsck /dev/sdb1
Password:
e2fsck 1.42 (29-Nov-2011)
e2fsck: Superblock invalid, trying backup blocks...
e2fsck: Bad magic number in super-block while trying to open /dev/sdb1
dumpe2fs
also:
$ sudo dumpe2fs /dev/sdb1
dumpe2fs 1.42 (29-Nov-2011)
dumpe2fs: Bad magic number in super-block while trying to open /dev/sdb1
mke2fs -n
(note, -n
) returns the superblocks:
$ sudo mke2fs -n /dev/sdb1
mke2fs 1.42 (29-Nov-2011)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
61054976 inodes, 244190363 blocks
12209518 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
7453 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968,
102400000, 214990848
... but trying "e2fsck -b [block]" for each block fails:
$ sudo e2fsck -b 71663616 /dev/sdb1
e2fsck 1.42 (29-Nov-2011)
e2fsck: Invalid argument while trying to open /dev/sdb1
However as I understand, these are where the superblocks were when the filesystem was created, which does not necessarily mean they are still intact.
I've also ran a testdisk
deep search if anyone can decypher the log. It mentions many entry like:
recover_EXT2: s_block_group_nr=1/7452, s_mnt_count=6/20,
s_blocks_per_group=32768, s_inodes_per_group=8192
recover_EXT2: s_blocksize=4096
recover_EXT2: s_blocks_count 244190363
recover_EXT2: part_size 1953522904
recover_EXT2: "e2fsck -b 32768 -B 4096 device" may be needed
Running e2fsck with those values gives:
e2fsck: Bad magic number in super-block while trying to open /dev/sdb1
I tried that with all superblocks in the testdisk.log
for i in $(grep e2fsck testdisk.log | uniq | cut -d " " -f 4); do
sudo e2fsck -b $i -B 4096 /dev/sdb1
done
... all with the same e2fsck
error message.
In my last attempt, I tried different filesystem offsets. For each offset i
, where i
is one of 31744, 32768, 1048064, 1049088:
$ sudo losetup -v -o $i /dev/loop0 /dev/sdb
... and running testdisk /dev/loop0
, I didn't find anything interesting.
I've been fairly exhaustive, but is there any way to recover the file system without resorting to low-level file recovery tools (foremost
/photorec
)?
sudo fdisk -l /dev/sdb
show? – Karlson Mar 02 '12 at 21:49testdisk
, as mentioned above, I tried different offsets usinglosetup
(i * 512
wherei
is one of 62, 64, 2047 or 2049). – tlvince Mar 03 '12 at 11:09