USB 3 external HDD unmounted while reading/writing

I have a Dell Vostro 3560 with 4 USB(All blue)

My linux version is: 17.1 Rebecca Xfce-x64
$ uname -a
Linux 3.16.0-45-generic #60~14.04.1-Ubuntu SMP Fri Jul 24 21:16:23 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

WHile a heavy load on hdd it is suddenly unmounts - like generating checksum on a large 42GB file
$ md5sum vm-disk2.vmdk
md5sum: vm-disk2.vmdk: Input/output error

This is a Delock external hdd with eSATAp+USB20+USB30 interface.

Sometimes needs to unplug and replug to remounts although power led is on.
It seems it losts power then remounts again.

When connected and mounted it is USB3.0
~ $ lsusb
Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 005: ID 1bcf:2895 Sunplus Innovation Technology Inc.
Bus 001 Device 004: ID 0bda:0129 Realtek Semiconductor Corp. RTS5129 Card Reader Controller
Bus 001 Device 003: ID 138a:0011 Validity Sensors, Inc. VFS5011 Fingerprint Reader
Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 004 Device 004: ID 152d:0551 JMicron Technology Corp. / JMicron USA Technology Corp.
Bus 004 Device 003: ID 1058:0740 Western Digital Technologies, Inc. My Passport
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 003 Device 006: ID 413c:2011 Dell Computer Corp. Multimedia Pro Keyboard
Bus 003 Device 005: ID 413c:1005 Dell Computer Corp. Multimedia Pro Keyboard Hub
Bus 003 Device 004: ID 046d:c52b Logitech, Inc. Unifying Receiver
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

~ $ lsusb -t
/: Bus 04.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 5000M
    |__ Port 3: Dev 3, If 0, Class=Mass Storage, Driver=usb-storage, 5000M
    |__ Port 4: Dev 5, If 0, Class=Mass Storage, Driver=usb-storage, 5000M
/: Bus 03.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 480M
    |__ Port 1: Dev 4, If 0, Class=Human Interface Device, Driver=usbhid, 12M
    |__ Port 1: Dev 4, If 1, Class=Human Interface Device, Driver=usbhid, 12M
    |__ Port 1: Dev 4, If 2, Class=Human Interface Device, Driver=usbhid, 12M
    |__ Port 2: Dev 5, If 0, Class=Hub, Driver=hub/3p, 12M
        |__ Port 1: Dev 6, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
        |__ Port 1: Dev 6, If 1, Class=Human Interface Device, Driver=usbhid, 1.5M
/: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/2p, 480M
    |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/8p, 480M
/: Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/2p, 480M
    |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/6p, 480M
        |__ Port 1: Dev 3, If 0, Class=Vendor Specific Class, Driver=, 12M
        |__ Port 3: Dev 4, If 0, Class=Vendor Specific Class, Driver=rtsx_usb, 480M
        |__ Port 5: Dev 5, If 0, Class=Video, Driver=uvcvideo, 480M
        |__ Port 5: Dev 5, If 1, Class=Video, Driver=uvcvideo, 480M

~ $ sudo hdparm -tT /dev/sdc

/dev/sdc:
 Timing cached reads: 20894 MB in 2.00 seconds = 10456.85 MB/sec
 Timing buffered disk reads: 324 MB in 3.02 seconds = 107.36 MB/sec

Could it be a device driver issue in linux?

Thanks!