3 days ago, I encountered an error while moving a folder of about 3 GB from my USB stick to my hard disk using GUI. After 1.2 GB of the files are moved, the progress bar of the program just remained unchanged. I left the seat in front of my computer and did something else. Returning to the seat after half an hour, the situation had NOT been better. The displayed remaining time was still “unknown”.
The I clicked the cancel button to stop the process, but it simply hangs. After terminating the process from the “System Monitor” (another GUI program), the read/write speed of the USB stick became extremely low. Instead of blinking frequently, the light bulb inside the USB stick went on and off slowing during a read/write operation.
In /var/log/syslog.1, it says
[ 627.152020] usb 2-1: reset high-speed USB device number 4 using ehci_hcd
[ 658.128020] usb 2-1: reset high-speed USB device number 4 using ehci_hcd
[ 658.493165] sd 3:0:0:0: [sdf] Unhandled error code
[ 658.493169] sd 3:0:0:0: [sdf] Result: hostbyte=DID_ABORT driverbyte=DRIVER_OK
[ 658.493174] sd 3:0:0:0: [sdf] CDB: Write(10): 2a 00 00 54 e9 30 00 00 01 00
[ 658.493188] end_request: I/O error, dev sdf, sector 5564720
[ 658.494531] quiet_error: 39 callbacks suppressed
[ 658.494533] Buffer I/O error on device sdf1, logical block 5564658
[ 658.495808] lost page write due to I/O error on sdf1
Oh! I need to recover the data! And I’ve found GNU ddrescue an excellent tool for the task. No expensive recovery plans are needed. Just ddrescue on a bootable media and some free space in a storage device will do.
It’s important to note that the data recovery program should never be run on the damaged device. Otherwise, further damage will be done to the damaged device.1 In addition, I don’t recommend running the data rescue tool on the operating system(s) installed on your hard disk. The process takes a long time, so “patience is key”.2
Booted into the CLI of Ubuntu Rescue Remix
12.04, I first formatted the D drive into an empty NTFS partition
after backing up the data on that device. (i.e. /dev/sda5)
After that , I ran the following command:3
$ ddrescue -r1 -n -S -v /dev/sdxm /dev/sdyn [logfile]
# Substitute x with the appropriate partition letter of the source partition
# Substitute y with the appropriate partition letter of the destination partition
# Substitute m with the appropriate partition number of the source partition
# Substitute n with the appropriate partition number of the destination partition
Note: This process is irreverisible so do it carefully.
In the screenshot below, x=f, y=a, m=1, n=5, and
logfile='backup1.log'.
But the program refused to work, so I have to --force it to work.
o create a new empty DOS partition table
p print the partition table
q quit without saving changes
s create a new empty Sun disklabel
t change a partition's system id
u change display/entry units
v verify the partition table
w write table to disk and exit
x extra functionality (experts only)
Command (m for help): l
0 Empty c FAT32 LBA 1e Hidd FAT16 LBA 52 CP/M 80 Minix <1.4a 9f BSD/OS bf Solaris eb BeOS fs
1 FAT12 e FAT16 LBA 24 NEC DOS 53 OnTrackDM6 Aux3 81 Minix >1.4b a0 Thinkpad hib c1 DRDOS/2 FAT12 ee GPT
2 XENIX root f Extended LBA 39 Plan 9 54 OnTrack DM6 82 Linux swap a5 FreeBSD c4 DRDOS/2 smFAT16 ef EFI FAT
3 XENIX usr 10 OPUS 3c PMagic recovery 55 EZ Drive 83 Linux a6 OpenBSD c6 DRDOS/2 FAT16 f0 Lnx/PA-RISC bt
4 Small FAT16 11 Hidden FAT12 40 Venix 80286 56 Golden Bow 84 OS/2 hidden C: a7 NeXTSTEP c7 Syrinx f1 SpeedStor
5 Extended 12 Compaq diag 41 PPC PReP Boot 5c Priam Edisk 85 Linux extended a8 Darwin UFS da Non-FS data f2 DOS secondary
6 FAT16 14 Hidd Sm FAT16 42 SFS 61 SpeedStor 86 NTFS volume set a9 NetBSD db CP/M / CTOS f4 SpeedStor
7 HPFS/NTFS 16 Hidd FAT16 4d QNX4.x 63 GNU HURD/SysV 87 NTFS volume set ab Darwin boot de Dell Utility fd Lnx RAID auto
8 AIX 17 Hidd HPFS/NTFS 4e QNX4.x 2nd part 64 Netware 286 88 Linux plaintext b7 BSDI fs df BootIt fe LANstep
9 AIX bootable 18 AST SmartSleep 4f QNX4.x 3rd part 65 Netware 386 8e Linux LVM b8 BSDI swap e1 DOS access ff XENIX BBT
a OS/2 boot mgr 1b Hidd FAT32 50 OnTrack DM 70 DiskSec MltBoot 93 Amoeba bb Boot Wizard Hid e3 DOS R/O
b FAT32 1c Hidd FAT32 LBA 51 OnTrackDM6 Aux1 75 PC/IX 94 Amoeba BBT be Solaris boot e4 SpeedStor
Command (m for help): x
Expert command (m for help): m
Command action
b move beginning of data in a partition
c change number of cylinders
e list extended partitions
f fix partition order
g create an IRIX (SGI) partition table
h change number of heads
m print this menu
p print the partition table
q quit without saving changes
r return to the main menu
s change number of sectors/track
v verify the partition table
w write table to disk and exit
Expert command (m for help): q
root@ubuntu:~# ddrescue -r1 -n -S -v /dev/sdf1 /dev/sda5 backup1.log
ddrescue: Output file exists and is not a regular file.
ddrescue: Use `--force' if you really want to overwrite it, but be
ddrescue: aware that all existing data in output file will be lost.
Try `ddrescue --help' for more information.
root@ubuntu:~# ls
root@ubuntu:~# ddrescue -r1 -n -S -f -v /dev/sdf1 /dev/sda5 backup1.log
About to copy 3999 MBytes from /dev/sdf1 to /dev/sda5
Starting positions: infile = 0 B, outfile = 0 B
Copy block size: 128 sectors
Sector size: 512 bytes
Max retries: 1
Direct: no Sparse: yes Split: no Truncate: no
Press Ctrl-C to interrupt
Initial status (read from logfile)
rescued: 0 B, errsize: 0 B, errors: 0
Current status
rescued: 377286 kB, errsize: 4096 B, current rate: 2686 kB/s
rescued: 594792 kB, errsize: 12288 B, current rate: 1179 kB/s
ipos: 594804 kB, errors: 2, average rate: 389 kB/s
opos: 594804 kB, time from last successful read: 0 s
Copying non-tried blocks...
Captured using screendump.
The program read the blocks fast initially but it gradually slowed down. After running the command for over 20 hours, over 3700 MB of the data had been read. Although there’s just about 400 MB to go, according to the average speed at that moment, it was an hour to recover 10 MB of the data. What’s worse, the average speed was getting slower and slower! (Later, from GeekyProjects, I realised that the heat of the devices inhibits the process, and the logfile file feature enables users to pause the job.45) Therefore, always use a logfile.6
Without adequate knowledge on GNU ddrescue, I stopped the task with
<C-c>, but it took the computer several minutes to receive this
input. But what’s next for an incomplete task? The files don’t
occupy the whole USB stick. It might took me another day if I waited
for some while and then resumed the task. At that moment, I decided
to try mounting the destination partition /dev/sdyn. Thinking that
the destination was a NTFS partition from the partition table rendered
by fdisk -l, I tried mount -t ntfs /dev/sdyn, but the computer
wouldn’t let me go. I was fortunate to be stopped by this error.
Otherwise, I think I would do another harm to the file system. This
time, I let mount to automatically decide the partition type by
removing the -t flag. It worked! I could browse and open the file
there. After that, I copied the files to a safe place (i.e. a
normal data storage device) Finally, I’ve found that most of the
files were salvaged, despite some corruption of the multimedia files.
Since then, I’ve really learnt a lesson: don’t to use GUI for
copying big files, always use commands. Secondly, never use mv
for big files, use cp instead.
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Disk Cloning (for Data Recovery) with GNU ddrescue by Alan Berman. ↩
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Ibid. ↩
-
Ibid. ↩
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How to Recover Data Even When Hard Drive is Damaged by Pablo Garcia. ↩