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I have a Mediasonic Smart Drive SuperSpeed 3.5" SATA HDD External Enclosure - USB 3.0 [HD6-SU3-BK]. It has the VIA VL700 - Super-Speed USB 3.0 to SATA controller which is supposed to support 3TB drives. The drive is an Advanced Format 3TB WDC WD30EZRX. I'm running 64bit Oneiric with the standard 3.0.0-16-generic kernel.

usb controller:
                       ATI SB700/SB800 USB OHCI0 Controller
                       ATI SB700/SB800 USB EHCI Controller
                       ATI SB700/SB800 USB OHCI0 Controller
                       ATI SB700/SB800 USB EHCI Controller
                       ATI SB700/SB800 USB OHCI2 Controller
                       ATI SB700/SB800 USB OHCI0 Controller
                       ATI SB700/SB800 USB EHCI Controller
                       NEC USB Controller

When the drive is connected to the internal SATA controller, I can access the whole 3TB, partition it with a GPT table and format it using XFS. When I put the drive in the enclosure, I can only see 746.52 GB.

Here's how the kernel sees the drive when it's connected to the internal SATA interface.

2.855426] scsi 6:0:0:0: Direct-Access     ATA      WDC WD30EZRX-00M 80.0 PQ: 0 ANSI: 5
[    2.855608] sd 6:0:0:0: [sdc] 5860533168 512-byte logical blocks: (3.00 TB/2.72 TiB)
[    2.855611] sd 6:0:0:0: [sdc] 4096-byte physical blocks
[    2.855619] sd 6:0:0:0: Attached scsi generic sg2 type 0

Here's how the kernel sees the drive when connected via the USB enclosure.

[605703.368137] usb 2-5: new high speed USB device number 3 using ehci_hcd
[605703.830770] Initializing USB Mass Storage driver...
[605703.831288] scsi10 : usb-storage 2-5:1.0
[605703.831626] usbcore: registered new interface driver usb-storage
[605703.831632] USB Mass Storage support registered.
[605719.251982] scsi 10:0:0:0: Direct-Access     WDC WD30 EZRX-00MMMB0     80.0 PQ: 0 ANSI: 2
[605719.254314] sd 10:0:0:0: Attached scsi generic sg2 type 0
[605719.258115] sd 10:0:0:0: [sdc] 1565565869 512-byte logical blocks: (801 GB/746 GiB)

See how internally there's 5,860,533,168 logical blocks and externally only 1,565,565,869.

I also noticed that SATA reports WDC WD30EZRX-00M 80.0 PQ: 0 ANSI: 5 while USB reports WDC WD30 EZRX-00MMMB0 80.0 PQ: 0 ANSI: 2 What's the difference between the two? Could this be the problem?

When connected to the SATA controller, parted says:

Model: ATA WDC WD30EZRX-00M (scsi)
Disk /dev/sdb: 3001GB
Sector size (logical/physical): 512B/4096B
Partition Table: gpt

Number  Start   End     Size    File system  Name  Flags
 1      1049kB  3001GB  3001GB  xfs

How can I access the whole drive when it's in the enclosure? Do I need an updated kernel/driver?

share|improve this question
[...]The enclosure manufacturer informed me that the enclosure works with Windows and OSX but not with Linux.[..] I think they know better?..probably an updated kernel will have the driver you need, probably not. – Uri Herrera Feb 16 '12 at 4:08
I have no reason to believe this as it seems to be backwards but is your drive an advanced format drive (4096 byte blocks)? – Huckle Feb 16 '12 at 5:33
@UriHerrera That was a misleading comment. After a tech had tried to to get it to work with his Linux system, he came to the conclusion that it didn't work with Linux. It wasn't the manufacturer's official position. – Richard Ayotte Feb 16 '12 at 12:52
@Huckle Yes, it is an Advanced Format drive. – Richard Ayotte Feb 16 '12 at 12:53
The ANSI might refer to ATA-2 and ATA-5 I found this while googling. – Huckle Feb 16 '12 at 15:33

This happens, at times, on Windows and OS X computers as well. If you do not have data on the drive you may want to try reformatting the drive.

First delete all partitions on the disk, unmount the disk, then remount the disk. If you then can see the entire drive try reformatting the drive while in the USB enclosure.

If this does not work or you have data on the drive can you give us more information about the partitions on the drive?

share|improve this answer
I don't think this has anything to do with how the drive was formatted. The kernel reports that the drive has 5,860,533,168 logical blocks when plugged directly to the SATA interface and reports only 1,565,565,869 when in the enclosure. The number of blocks on the drive is determined at a lower level and is independent of the format. – Richard Ayotte May 10 '12 at 16:09
up vote 1 down vote accepted

After much discussion with Mediasonic, it turns out that there's a firmware problem with the enclosure.

They provided a firmware update tool but it only works on Windows.

I couldn't get the update tool to work so they've sent me a board with the firmware already updated.

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