Hi,
I am using OSMC Alpha 4 on a Raspberry Pi 2 and is trying to mount an external HDD. I do have a powered USB hub, but the harddrive doesn’t get detected (doesn’t show up with “sudo fdisk -l”). The following log is what I got from dmesg when I plugged in the hdd. It appears that the hdd got detected, but something went wrong after that. Can somebody please let me know what could be going wrong? Am I missing something obvious here - I am a newbie to RPi! 
-Jo
[ 566.837109] usb 1-1.2.1.4: new full-speed USB device number 8 using dwc_otg
[ 567.018315] usb 1-1.2.1.4: not running at top speed; connect to a high speed hub
[ 567.020681] usb 1-1.2.1.4: New USB device found, idVendor=1058, idProduct=0820
[ 567.020704] usb 1-1.2.1.4: New USB device strings: Mfr=1, Product=2, SerialNumber=5
[ 567.020722] usb 1-1.2.1.4: Product: My Passport 0820
[ 567.020739] usb 1-1.2.1.4: Manufacturer: Western Digital
[ 567.020756] usb 1-1.2.1.4: SerialNumber: 3658373251392431343F5A32
[ 567.022326] usb-storage 1-1.2.1.4:1.0: USB Mass Storage device detected
[ 567.025680] scsi host2: usb-storage 1-1.2.1.4:1.0
[ 568.018257] scsi 2:0:0:0: Direct-Access WD My Passport 0820 1012 PQ: 0 ANSI: 6
[ 568.019600] sd 2:0:0:0: Attached scsi generic sg1 type 0
[ 568.022590] scsi 2:0:0:1: Enclosure WD SES Device 1012 PQ: 0 ANSI: 6
[ 568.027720] sd 2:0:0:0: [sdb] Spinning up disk…
[ 568.034135] scsi 2:0:0:1: Attached scsi generic sg2 type 13
[ 569.036696] …not responding…
[ 642.027096] usb 1-1.2.2: reset full-speed USB device number 6 using dwc_otg
[ 657.107115] usb 1-1.2.2: device descriptor read/64, error -110
[ 672.296996] usb 1-1.2.2: device descriptor read/64, error -110
[ 672.487029] usb 1-1.2.2: reset full-speed USB device number 6 using dwc_otg
[ 687.567039] usb 1-1.2.2: device descriptor read/64, error -110
[ 702.757054] usb 1-1.2.2: device descriptor read/64, error -110
[ 702.947087] usb 1-1.2.2: reset full-speed USB device number 6 using dwc_otg
[ 707.966748] usb 1-1.2.2: device descriptor read/8, error -110
[ 713.096737] usb 1-1.2.2: device descriptor read/8, error -110
[ 713.287100] usb 1-1.2.2: reset full-speed USB device number 6 using dwc_otg
[ 718.306760] usb 1-1.2.2: device descriptor read/8, error -110
[ 723.436750] usb 1-1.2.2: device descriptor read/8, error -110
[ 723.547823] usb 1-1.2.2: USB disconnect, device number 6
[ 723.566903] sd 0:0:0:0: [sda]
[ 723.566940] Result: hostbyte=0x01 driverbyte=0x00
[ 723.566958] sd 0:0:0:0: [sda] CDB:
[ 723.566972] cdb[0]=0x28: 28 00 00 00 00 00 00 00 08 00
[ 723.567041] blk_update_request: I/O error, dev sda, sector 0
[ 723.567088] Buffer I/O error on dev sda, logical block 0, async page read
[ 723.727186] sda: detected capacity change from 16008609792 to 0