How can a usb be detected but not show up anywhere?
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/exFATI 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 diskbut 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?
16 Answers
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 dmesghere 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: sde1so then i would try mounting that filesystem at /dev/sde1sudo mount /dev/sde1 /home/user/Desktop/foowhere 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.
Probably the partition table has gone all wrong. Your device should be listed in /dev/disk/by-id as @usb-GENERIC (something that resembles the description in line with scsi 10:0:0:0...
Check the symblink it leads to (probably will be /dev/sr1). Then you can create a new partition table by:
sudo fstab /dev/sr1Then proceed with creating new partition(s) using fstab commands.
It may not be your USB device, but your USB port may not be able to provide sufficient power for the device."
On my machine, most devices work fine, but I have one USB drive that only works when plugged into one of the rear ports, which are directly on the MB. Symptoms in this case are very similar to your results.
Options are to try a different port, or to get a powered USB hub.
In my case, it didn't work with any USB port. But while reading this answer I remembered that my HD adapter came with a double USB cable and everything worked pretty well when I used it.
If you canceled it it might have ended in a state where its not recognized by the OS so it doesn't mount, try lsusb, should be there, also, you didn't post the fdisk -l of when you did plug in the usb
When device shows up with lsusb command but is not assigned to a device (/dev/*), then try a USB port directly connected to the motherboard, usually at the back of your desktop.
2If you happen to be using a removable SD card adapter like me, make sure the SD card has been inserted in the correct orientation. If not, you will see a /dev/sdb device poped up in dmesg but not in fdisk -l and got terribly confused.
