"Replace disk with larger one"

[ecarsontc]

Hello All,

Newbie here - Using NAS AS6202T, RAID 1 with 2 3TB Disks.
I have just replaced one WD Red 3TB disk with another, with the goal of storing one offsite as a potential backup.
All gone well (following a restart) except now getting message "Please replace the disk with a larger one" for Disk 1 (the one I replaced)
Any ideas on this?
With thanks in advance,
Toby

[snapshot]

Is the new drive exactly the same model as the originals? There have been more than one model of WD Red so it's possible that the new one might have a marginally lower capacity.