The new 6TB RED is likely to be SMR, not CMR/PMR. (Shingled Magnetic Recording), and one of the major concerns with these new WD SMR drives, is this use-case (what you're about to attempt) rebuilding arrays/adding an extra disk to a RAID 5 array, because an SMR drive has no downtime during this very extensive task, to do the required slower SMR background tasks.
If I was you I'd contact WD, explain the situation and ask for a replacement to a 6TB RED Pro or buy a Seagate Ironwolf NAS, both of which are CMR.
I wouldn't risk it with the 6TB RED, if it is one of the new SMR drives.
It won't be the same type of drive as the existing REDs you have.
Moving to new hardware : DSM 6.2-23739
in DSM 6.x
Posted · Edited by typhoontiger
Something to be aware of:
The new 6TB RED is likely to be SMR, not CMR/PMR. (Shingled Magnetic Recording), and one of the major concerns with these new WD SMR drives, is this use-case (what you're about to attempt) rebuilding arrays/adding an extra disk to a RAID 5 array, because an SMR drive has no downtime during this very extensive task, to do the required slower SMR background tasks.
If I was you I'd contact WD, explain the situation and ask for a replacement to a 6TB RED Pro or buy a Seagate Ironwolf NAS, both of which are CMR.
I wouldn't risk it with the 6TB RED, if it is one of the new SMR drives.
It won't be the same type of drive as the existing REDs you have.