• Thanks, that'smy guess too. The plan is to get a new 4 bay nas around Thanksgiving and then copy things over
  • tried without the usb, it still failed. But this time I did see an error in dmesg which said "unrecoverable I/O read error for block ". Although smart and the scan in zyxel's UI shows the disk is ok.
  • The 3rd disk is unrelated and is connected through external USB.
  • disk wasn't hot plugged and the partition exists. Didn't see anything in dmesg, I tried it twice (reformatted the new drive between each try), both times stopped around the same time. I see the original product description says up to 2 3TB drives, not sure if there's an actual 3TB limit. ~ # cat /proc/partitionsmajor minor…
  • The first time I tried to assemble it said resource is busy for one of the disk and I just had to run mdadm stop. I tried to put the disk back in the Nas, one of the hdd light is still red and won't boot so not sure if something is wrong with the disk. It might be something bad in the smaller partition. 
  • I bought another dock so I was able to assemble the array and mount it. Now I just need to buy another drive big enough to copy the data over
  • If I put one drive in, doesn't matter which side it will boot. If I put both disks in, the disk led for one of the drive will always turn red and it would not boot. So maybe one disk has some corruption so it fails during assemble, is there a way to repair it?
  • I only have 1 sata dock so I am unable to connect both disks simultaneously. Is it possible to fix the part that contains the firmware or make it boot without using that part (like from external USB)?