Terascale drive compatibility with NAS326

leonid32

Hi! I have purchased 2 Terascale v2 HDDs (Seagate ST8000NC0002) for my NAS326.
The goal was to replace 2 older 3TB drives in RAID1 with these 8TB ones.
And it does not work. The drives are recognized by NAS with no problems, when I replace one of the old drives with the new one, NAS reports RAID1 volume as degraded and starts repair process.
But when repair ends (with no errors), RAID1 volume is still reported as degraded, and the new drive is marked as hot swap. Rebooting NAS triggers repair again.
I tried it all a number of times, with both drives - there is no difference.
Can anybody advice how to solve this problem?

I am thinking of backing up the data, swapping both drives, creating a brand new RAID1 volume and restoring from backup, but before I attempt this, I'd like to be sure there is no other way... What does the community think?

ikubuf

If you have done the backup already, I think it is more easier to create a brand new Raid 1 volume than dig into the issue.

May I know how do you do to replace the disk? 
Do you shut down the NAS before you unplug the disk?