with 2TB at $80, I would not wait.
I use my 2 bay without RAID. I set it up (Synology) for two independent volumes, each with a different file system. And automatic file versioning copies from one to the other.
Plus a 2.5 in. USB3 drive for backup, kept out of sight of thieves.
Don't get Green disks. They are not suitable for NAS use.
Red disks are a much better choice.
WD 'red' not worth a price premium
Reds aren't really that much more than HGST or other good drives.
Seagate has been complete garbage for the last couple of years. I've replaced hundreds of them in both home and enterprise setups.
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