Few days ago I bought new disk dock as the old one was not capable of working with 4 TB disks. My pick was Raidsonic ICX BOX IB-121CL-U3 with two disk slots. By documentation it is capable of JBOD – the two HDDs are detected as two independent drives. Previously I had copied my smalled external disks to new ones (4TB disks were inside PC , one by one.)
For my surprise two simultaneous disks were not recognized in disk dock. If only one of them was inserted then all was fine. Opening Computer Managenet and from there Disk Management revealed the reason :
Disk 2 is offline because it has a signature collision.
After some googling the solution for Windows 7 was found.
- Run DiskPart
- list disks
- select disk 2 (in my case)
- uniqueid disk
It did the trick (after hdd dock power off/on)