How do I recover partitions from a drive I removed from my NAS?

[mattshelton]

I have a 4-bay DS918+ with two 4Tb drives and two 8Tb drives. The 8s were recent additions, replacing two 3Tb units. I'd like to make use of the 3Tbs as external drives for home computers, however their partition tables are corrupted. Both show 800Gb of unpartitioned space.

I've mounted them each on a Mac and Ubuntu machines. I've tried wiping the partition tables. I tried using dd to write zeroes to the disk and it stops at 800Gb. I cannot make any machine see the entire 3Tb of space.

Any thoughts on how I can reset the number of blocks, or are these drives toast?

 

[EAZ1964]

did you try to repair using a disk utility like seatools or wd utilities?
If formatting does not work, I would say: scrap them