I have a failed Thecus 7700 Pro v1 NAS unit, that is completely inaccssible over the network and has no video output (- tried connecting a stripped VGA cable to the empty VGA socket on the motherboard as suggested in this blog post but got no VGA output detected). The system just hangs at the Self Testing... stage on boot, indicatd by the orange status LED. It is likely given the age of the NAS that either or both of the DOM and built-in NICs have failed.

As a result I would like to check whether or not it is possible to separately image each of the seven 2Tb hdds that form the RAID 6 array booted from a bootable USB (Linux) flash drive on a PC (32Gb RAM) - to free up one of the available SATA ports. A 12Tb hdd is currently available in the same PC to store the disk images.

The aim is to use the images created to recover the data and to reduce the risk of failure of the original hdds. I also would also like to make sure that any disk images created are done so without writing to the original RAID disks in th process.

Further Internet searches uncovered this other blog post to be able to recover the data but assumes, as nearly all other recovery instructions do, that access login to the NAS is actually available.

Any guidance/advice as to how best to achieve this with linux tools would be greatly appreciated.

1 Answer 1


The imaging of the RAID6 array drives has been achieved as follows:

Step 1 - Required Program

  • Make sure the following programs are installed:
  • Run the following commands to install the programs, if necessary:
    sudo apt-get update
    sudo apt-get install dc3dd
    sudo apt-get install smartmontools

Step 2 - Attach Source & Target Drives

  • Shutdown the computer being used to recover the data.
  • Attach target empty target drive for the drive images.
  • Attach RAID6 array source drive.
  • Boot the computer into Debian Bullseye or Kali Linux 2023.01.
  • Check device allocation and device sector size:
    sudo fdisk -l
  • Format and mount the target drive for the RAID6 array drive images.
  • Run gparted
  • Select the correct drive id of the target drive for the drive images from the drives dropdown menu (- top right of the program window).
  • From the program menu select the Device > Create Partition Table… option.
  • From the program menu select the Partition > New option.
  • Select the File system > exfat option.
  • Click on the Add button.
  • From the program menu select the Edit > Apply All Operations option.
  • Be patient while the partition operations complete.
  • Close the gparted program window.

Step 3 - Image Drives

Repeat the following commands to image the HDDs one at a time, shutting down the PC, removing and connecting the RAID6 array drives as required.

  • Check device allocation and device sector size:
    $ sudo fdisk -l
    512 bytes sector size confirmed.
  • Check RAID6 array drive smart status:
    sudo sudo smartctl -a /dev/sd[id] > /home/[user path]/hdd[id]smart.log
  • Image RAID6 array drive and output hash and image log files:
    sudo dc3dd if=/dev/[sd source id] of=/dev/[sd target id]/recovery/hdd[id].img hash=sha256 hlog=/home/[user path]/hdd[id]hash.log log=/home/[user path]/hdd[id].log

Note: Each 2Tb drive took a little over 6 hours for the imaging to complete.

Step 4 - Backup Drive Images

Backup all the drive images to another backup drive before proceeding further. This is important, don't skip!

Hope this helps someone else.

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