USB 2.0 Issues
When using USB 2.0 devices, some problems may be present. In older versions of Ubuntu this can be worked around by unloading the appropriate kernel module:
sudo rmmod ehci_hcd
Recent version of Ubuntu, and Linux in general, need only a few kernel modules to support USB mass storage devices. Everything else is handled automatically by hal and udev.
When you connect a USB device you should get a message in /var/log/kern.log like this one:
[ 5762.680031] usb 1-2: new high speed USB device using ehci_hcd and address 4 [ 5763.340703] usb 1-2: configuration #1 chosen from 1 choice
However, if that device is a USB storage device (flash drive) and is not found anywhere, you may have a missing module.
Make sure the following modules are inserted:
sudo modprobe hid sudo modprobe usbhid sudo modprobe usb_storage
Particularly, when usb_storage is inserted, you should get a message like this one:
[ 712.617279] Initializing USB Mass Storage driver... [ 712.617352] usbcore: registered new interface driver usb-storage [ 712.618240] USB Mass Storage support registered.
Now, if you insert your flash drive again, it will be assigned a SATA interface and will be mounted:
[ 727.076031] usb 1-2: new high speed USB device using ehci_hcd and address 4 [ 727.736450] usb 1-2: configuration #1 chosen from 1 choice [ 727.757057] scsi4 : SCSI emulation for USB Mass Storage devices [ 732.761591] scsi 4:0:0:0: Direct-Access HP v100w 4096 PQ: 0 ANSI: 0 CCS [ 732.763848] sd 4:0:0:0: Attached scsi generic sg2 type 0 [ 732.765576] sd 4:0:0:0: [sdb] 7831552 512-byte logical blocks: (4.00 GB/3.73 GiB) [ 732.772884] sd 4:0:0:0: [sdb] Write Protect is off [ 732.776462] sdb: sdb1 [ 732.782332] sd 4:0:0:0: [sdb] Attached SCSI removable disk
Buffer I/O Errors
If you see errors related to Buffer I/O when attaching a USB Storage device, there are two ways to work around it. First, try using varying max_sectors settings, as such:
sudo sh -c "echo 120 > /sys/block/sda/queue/max_sectors_kb"
Try values of 120, 64 and 32.
If this does not resolve the issue, then you may need an unusual_dev entry for your device. It would look something like this:
UNUSUAL_DEV(0x03eb , 0x2002, 0x0100, 0x9999, "Generic", "MusicDrive", US_SC_DEVICE, US_PR_DEVICE, NULL, US_FL_IGNORE_RESIDUE),
The vendor and device ID's can be obtained from the output of "lsusb". The entry would be placed in drivers/usb/storage/unusual_devs.h. If you cannot compile your own kernel, please file a bug report, and we'll attempt to compile a test module for you.
If you are filing a bug report, please include the following as attachments along with a detailed description of your problem.
Initiate the problem situation, then quickly get the output of dmesg
Output of uname -a
Output of lsb_release -a
Output of lsusb -v
- any other data relevant to your problem
For help with mounting external drives, see Mount/USB.