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When I boot, the device I'm looking for shows up but it isn't detected in the file system. I have two drives, a 500g and a 1Tb in a dual ...
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  1. #1
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    Question usb external drive doesn't get detected


    When I boot, the device I'm looking for shows up but it isn't detected in the file system. I have two drives, a 500g and a 1Tb in a dual usb case.

    When I do sudo fdisk -l, I get:

    Disk /dev/sda: 200.0 GB, 200049647616 bytes
    255 heads, 63 sectors/track, 24321 cylinders
    Units = cylinders of 16065 * 512 = 8225280 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    Disk identifier: 0x00046636

    Device Boot Start End Blocks Id System
    /dev/sda1 * 1 23330 187395072 83 Linux
    /dev/sda2 23330 24322 7963649 5 Extended
    /dev/sda5 23330 24322 7963648 82 Linux swap / Solaris

    Disk /dev/sdb: 500.1 GB, 500107862016 bytes
    255 heads, 63 sectors/track, 60801 cylinders
    Units = cylinders of 16065 * 512 = 8225280 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    Disk identifier: 0x000c6e34

    Device Boot Start End Blocks Id System
    /dev/sdb1 * 1 60802 488383488 7 HPFS/NTFS

    Disk /dev/sdc: 1000.2 GB, 1000204886016 bytes
    255 heads, 63 sectors/track, 121601 cylinders
    Units = cylinders of 16065 * 512 = 8225280 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    Disk identifier: 0x000a4f3b

    Device Boot Start End Blocks Id System
    /dev/sdc1 1 120455 967546880 83 Linux
    /dev/sdc2 120455 121602 9212929 5 Extended
    /dev/sdc5 120455 121602 9212928 82 Linux swap / Solaris

    The 500g drive shows up as "New Volume" in the system and works fine. Okay, I tried installing Ubuntu 10.04 on this laptop. It does the same thing. (since I have all my data on the 500G drive, wipes/installs are no big deal).

    The ironic thing is that when I went to install Ubuntu, the disk recognized all three drives; the 200g laptop, the 500g external and the 1Tb external.

    Now that Ubuntu is installed, however, it still won't recognize the 1Tb drive.


  2. #2
    Linux Engineer hazel's Avatar
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    Try typing dmesg|grep sdc. This will throw up lines in the kernel's startup messages that relate to your 1TB drive. Does the kernel acknowledge it? If so, you should be able to mount the individual partitions on it by hand. I trust the good old mount command a lot more than I trust Ubuntu's automounting.
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  3. #3
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    When I tried that, I got this output:

    dmesg|grep sdc

    [ 2.361493] sd 3:0:0:0: [sdc] 390721968 512-byte logical blocks: (200 GB/186 GiB)
    [ 2.361592] sd 3:0:0:0: [sdc] Write Protect is off
    [ 2.361596] sd 3:0:0:0: [sdc] Mode Sense: 00 3a 00 00
    [ 2.361655] sd 3:0:0:0: [sdc] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
    [ 2.361913] sdc: sdc1 sdc2 < sdc5 >
    [ 2.433978] sd 3:0:0:0: [sdc] Attached SCSI disk
    [ 3.885782] EXT4-fs (sdc1): mounted filesystem with ordered data mode. Opts: (null)
    [ 18.054339] Adding 7963644k swap on /dev/sdc5. Priority:-1 extents:1 across:7963644k
    [ 18.348611] EXT4-fs (sdc1): re-mounted. Opts: errors=remount-ro
    [ 22.823808] EXT4-fs (sdc1): re-mounted. Opts: errors=remount-ro,commit=0
    [ 57.698539] EXT4-fs (sdc1): re-mounted. Opts: errors=remount-ro,commit=0

  4. #4
    Linux Guru
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    Now that Ubuntu is installed, however, it still won't recognize the 1Tb drive.
    What does this mean? The system "sees" the drive, as shown by the fdisk output.

    Code:
    Device Boot Start End Blocks Id System
    /dev/sdc1 1 120455 967546880 83 Linux
    /dev/sdc2 120455 121602 9212929 5 Extended
    /dev/sdc5 120455 121602 9212928 82 Linux swap / Solaris
    That looks like only /dev/sdc1 has data and the dmesg output shows it's an ext4 filesystem. If it's mounted, it will show up in the df command:

    Code:
    df -ah
    If it's not mounted, you can manually mount it:

    Code:
    sudo mount /dev/sdc1 /some/empty/folder

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