Ubuntu – How to a usb be detected but not show up anywhere

mountusb-drive

I started the morning by trying to create a bootable usb using a 2gb stick and the startup disk creator. It seemed to run through the whole process just fine until it got to a screen that read something like "Creating memory partion" and which sat on 100% for about 45 minutes before I hit cancel and removed the usb stick.

Now the usb stick is not being detected as storage or…anything (even on my windows pc) though it does show up in the syslog.

Allow me to demonstrate. We start with the usb not plugged in:

[georgemauer@ubuntu:~]$ sudo fdisk -l                                     (04-04 16:01)

Disk /dev/sda: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders, total 976773168 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
Disk identifier: 0x994bdc0f

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1            2048    27650047    13824000   27  Hidden NTFS WinRE
/dev/sda2   *    27650048    27854847      102400    7  HPFS/NTFS/exFAT
/dev/sda3        27854848   976771119   474458136    7  HPFS/NTFS/exFAT

I plug in the usb:

[georgemauer@ubuntu:~]$ tail -f /var/log/syslog         
                       ***Snip***

Apr  4 15:01:18 ubuntu wpa_supplicant[1136]: WPA: Group rekeying completed with 00:24:36:ad:e7:3f [GTK=TKIP]
Apr  4 15:02:29  wpa_supplicant[1136]: last message repeated 3 times
Apr  4 15:02:29 ubuntu kernel: [22122.788133] usb 2-1: new high speed USB device number 13 using ehci_hcd
Apr  4 15:02:29 ubuntu kernel: [22122.923873] scsi10 : usb-storage 2-1:1.0
Apr  4 15:02:29 ubuntu mtp-probe: checking bus 2, device 13: "/sys/devices/pci0000:00/0000:00:13.2/usb2/2-1"
Apr  4 15:02:30 ubuntu mtp-probe: bus: 2, device: 13 was not an MTP device
Apr  4 15:02:30 ubuntu kernel: [22123.926154] scsi 10:0:0:0: Direct-Access     GENERIC  USB Mass Storage 1.00 PQ: 0 ANSI: 2
Apr  4 15:02:30 ubuntu kernel: [22124.105118] sd 10:0:0:0: Attached scsi generic sg1 type 0
Apr  4 15:02:30 ubuntu kernel: [22124.108212] sd 10:0:0:0: [sdb] Attached SCSI removable disk

but then:

[georgemauer@ubuntu:~]$ ls /mnt -alF                                      (04-04 16:02)
total 8
drwxr-xr-x  2 root root 4096 2011-04-21 12:51 ./
drwxr-xr-x 26 root root 4096 2012-03-31 13:16 ../
[georgemauer@ubuntu:~]$ ls /media -alF                                    (04-04 16:03)
total 8
drwxr-xr-x  2 root root 4096 2012-04-04 12:18 ./
drwxr-xr-x 26 root root 4096 2012-03-31 13:16 ../

What could be going on and how do I recover my usb key?

Best Answer

sudo lsusb is the first step. looking in /mnt or /media, or /anywherelse implies the hardware has been mounted. The hardware maybe plugged in but not mounted.

If you see the device listed, then you can look for the /dev/ assignment in dmesg here is dmesg output of when i just pluged a memory stick in my computer:

[10527.883515] sd 6:0:0:3: [sde] 126912 512-byte logical blocks: (64.9 MB/61.9 MiB)
[10527.884558] sd 6:0:0:3: [sde] Write Protect is on
[10527.884567] sd 6:0:0:3: [sde] Mode Sense: 03 00 80 00
[10527.885747] sd 6:0:0:3: [sde] No Caching mode page present
[10527.885755] sd 6:0:0:3: [sde] Assuming drive cache: write through
[10527.889253] sd 6:0:0:3: [sde] No Caching mode page present
[10527.889261] sd 6:0:0:3: [sde] Assuming drive cache: write through
[10527.892404]  sde: sde1

so then i would try mounting that filesystem at /dev/sde1 sudo mount /dev/sde1 /home/user/Desktop/foo where you mount your hardware, is somewhat trivial. /mnt /media /whocares it doesnt matter. (ignoring FHS, and assuming you wont try mounting in a place like root)

sudo fdisk -l will tell you the filesystem type and /dev/ assignment. fdisk -l however will not tell you anything, (strangely, it doesn't return "permission denied")

why use dmesg instead of fdisk? because using fdisk assumes your hardware is working. If your hardware fails, fdisk wont tell you. but dmesg will.