I'm trying to read an usb drive that until a few day ago seemed to be perfectly working. Today windows started to be unable to access or modify its content. Trying to reformat it with linux (arch distribution) there are a few strange things. The output of lsblk is (sdc is the faulty usb drive)

sda      8:0    0 149.1G  0 disk 
  sda1   8:1    0 149.1G  0 part /
  sda2   8:2    0  1007K  0 part 
sdb      8:16   0 465.8G  0 disk 
  sdb1   8:17   0 465.8G  0 part /mnt/toshibaExt
sdc      8:32   1     8M  0 disk 
sr0     11:0    1  1024M  0 rom

The output of lsblk -f is:

# lsblk -f
NAME   FSTYPE LABEL       UUID                                 MOUNTPOINT
  sda1 ext4               5711fd14-4c90-487f-a8fc-ae7923d54dc5 /
  sdb1 ntfs   TOSHIBA EXT 5ADEC4FBDEC4D085                     /mnt/toshibaExt

Trying to erase the content with dd results in

# dd if=/dev/zero of=/dev/sdc
dd: writing to ‘/dev/sdc’: No space left on device
16385+0 records in
16384+0 records out
8388608 bytes (8.4 MB) copied, 1.07083 s, 7.8 MB/s

Trying to create a new partition table with gparted, gparted sees in sdc a single chunk of unallocated memory of 8MiB, with

File System=unallocated
Size=8.00 MiB

If i try to create a new partition table from gparted, msdos type, no error is given in the gui but nothing seems to happen. In the terminal i have a "/dev/sdc: unrecognised disk label" error. Trying to create a new partition results in the error message: "no partition table found".

With fdisk, i tried to create a new partition with

#fdisk /dev/sdc
n p <enter> <enter> w

It says that a new partition 1 of type 'Linux' and of size 7 MiB has been created, but trying again with lsblk or gparted nothing seems to have changed.


The output of dmesg after plugging in the USB is:

[  931.543277] usb 5-7: new high-speed USB device number 7 using ehci-pci
[  931.668457] usb-storage 5-7:1.0: USB Mass Storage device detected
[  931.669171] scsi6 : usb-storage 5-7:1.0
[  932.670552] scsi 6:0:0:0: Direct-Access     Generic  Flash Disk 2.0   2.60 PQ: 0 ANSI: 2
[  932.671782] sd 6:0:0:0: [sdc] 16384 512-byte logical blocks: (8.38 MB/8.00 MiB)
[  932.672412] sd 6:0:0:0: [sdc] Write Protect is off
[  932.672419] sd 6:0:0:0: [sdc] Mode Sense: 0b 00 00 08
[  932.673030] sd 6:0:0:0: [sdc] No Caching mode page found
[  932.673036] sd 6:0:0:0: [sdc] Assuming drive cache: write through
[  932.677671]  sdc: unknown partition table
[  932.680661] sd 6:0:0:0: [sdc] Attached SCSI removable disk

EDIT2: Output of fdisk -l:

$ sudo fdisk /dev/sdc -l

Disk /dev/sdc: 8 MiB, 8388608 bytes, 16384 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
  • So gparted sees the correct device, right? And it is unmounted? In gparted, are you writing a new table (Device>Create Partition Table), writing over the unallocated sector, and then applying? And no errors?! And as a word of advice, you don't need to copy /dev/zero to the device. Gparted, fdisk, cfdisk, whatever will write over the old partition and write a new table for you. – Steven Walton Sep 1 '14 at 1:45
  • What does dmesg say about this device while you're accessing it? – slm Sep 1 '14 at 5:49
  • 1
    @StevenWalton gparted sees the device. The device is unmounted (I don't think I couldn't mount it anyway as there is no partition in it). I suspected that dd was useless, but it striked me the "no space left on device" message. Is that normal behavior in this circumstances? When I try to create the partition table (by Device->Create Partition Table) it seems to work for a few seconds, then it stops without error messages in the GUI and with the only "unrecognized partition table" msg in the terminal. The apply button is still disabled. – glS Sep 1 '14 at 9:37
  • @slm added to the post the output of dmesg – glS Sep 1 '14 at 9:40
  • @glance - sorry what does dmesg show after you access the device? This looks like what it shows just after you physically connect it to the computer. – slm Sep 1 '14 at 11:40

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