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I recently bought a 3 TB harddisk which I inserted into a external USB drive enclosure and connected it to linux debian.

Unfortunately it now shows up 2 separate physical drives: one with 2.19TB and one with 801 GB.

I have no idea why.

I upgraded to wheezy and kernel 3.2.48 but no difference.

Here is my dmesg output:

[ 4133.260187] usb 2-4: new high-speed USB device number 2 using ehci_hcd
[ 4133.414995] usb 2-4: New USB device found, idVendor=1bcf, idProduct=0c31
[ 4133.415003] usb 2-4: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 4133.415008] usb 2-4: Product: USB to Serial-ATA bridge
[ 4133.415012] usb 2-4: Manufacturer: Sunplus Innovation Technology
[ 4133.582155] Initializing USB Mass Storage driver...
[ 4133.582259] scsi8 : usb-storage 2-4:1.0
[ 4133.582316] usbcore: registered new interface driver usb-storage
[ 4133.582317] USB Mass Storage support registered.
[ 4134.582266] scsi 8:0:0:0: Direct-Access   Generic  External  0200 PQ: 0 ANSI: 4
[ 4134.584004] scsi 8:0:0:1: Direct-Access   Generic  External  0200 PQ: 0 ANSI: 4
[ 4134.584682] sd 8:0:0:0: Attached scsi generic sg6 type 0
[ 4134.584887] sd 8:0:0:1: Attached scsi generic sg7 type 0
[ 4134.586143] sd 8:0:0:0: [sdg] 4294967295 512-byte logical blocks: (2.19 TB/1.99 TiB)
[ 4134.587706] sd 8:0:0:1: [sdh] 1565565872 512-byte logical blocks: (801 GB/746 GiB)
[ 4134.594994] sd 8:0:0:0: [sdg] Write Protect is off
[ 4134.595005] sd 8:0:0:0: [sdg] Mode Sense: 38 00 00 00
[ 4134.601930] sd 8:0:0:1: [sdh] Write Protect is off
[ 4134.601933] sd 8:0:0:1: [sdh] Mode Sense: 38 00 00 00
[ 4134.608790] sd 8:0:0:0: [sdg] No Caching mode page present
[ 4134.612126] sd 8:0:0:0: [sdg] Assuming drive cache: write through
[ 4134.615642] sd 8:0:0:1: [sdh] No Caching mode page present
[ 4134.619021] sd 8:0:0:1: [sdh] Assuming drive cache: write through
[ 4134.631010] sd 8:0:0:0: [sdg] No Caching mode page present
[ 4134.634342] sd 8:0:0:0: [sdg] Assuming drive cache: write through
[ 4134.652110] sd 8:0:0:1: [sdh] No Caching mode page present
[ 4134.655459] sd 8:0:0:1: [sdh] Assuming drive cache: write through
[ 4134.687317]  sdg: unknown partition table
[ 4134.687749]  sdh: unknown partition table
[ 4134.710370] sd 8:0:0:0: [sdg] No Caching mode page present
[ 4134.713674] sd 8:0:0:0: [sdg] Assuming drive cache: write through
[ 4134.716994] sd 8:0:0:0: [sdg] Attached SCSI disk
[ 4134.717241] sd 8:0:0:1: [sdh] No Caching mode page present
[ 4134.720764] sd 8:0:0:1: [sdh] Assuming drive cache: write through
[ 4134.720768] sd 8:0:0:1: [sdh] Attached SCSI disk

Now I could just create two separate partitions and add them to one lvm assembly but since I have no idea why this is happening I first want to know why.

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migrated from serverfault.com Aug 6 '13 at 10:28

This question came from our site for professional system and network administrators.

3  
Something in your system doesn't support more then 2TB drives it would seem. You need to find the device, and replace it. –  Zoredache Aug 6 '13 at 6:00
    
Can you plug the 3 TB external harddisk into another computer, one which is not running Linux? It will be interesting to see if it is the drive enclosure which 'helpfully' presents the 3TB drive as two drives or if it is the OS. –  Hennes Aug 6 '13 at 11:18
    
Sorry for the delay.. i was on vacation. I just connected the drive to a windows pc, same result: two drives. Therefore it must be the usb2sata device which is responsible for the separation. Funny hint: there is nothing in the usb enclosure about it... *gah –  Dready Aug 20 '13 at 18:51

3 Answers 3

I think it's an MBR partition size limitation. Try to use parted to create GPT label.

(parted) mklabel gpt
(parted) mkpart primary 0 0
(parted) quit
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up vote 0 down vote accepted

The USB2SATA hardware device in the usb drive enclosure must be responsible because i get the same results on a different windows machine.

Nothing can be found in the usb drive enclosurements documentation but that does not mean anything.

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Since it seems to be showing up as two separate SCSI devices (8:0:0:0 and 8:0:0:1), I'm guessing the drive firmware is set up to do that, particularly since windows also thought it was two drives.

If it was just partitioning then it would still show up as one drive, not two.

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