Adding storage to server.

[Cronus94]

If it were me I’d be recreating my pool as a 6 or 8 wide RaidZ2 and then restoring the data from backup.

That's my plan. I plan on backing up my data to an external drive and recreating the pool with the extra two 4tb drives added (again in raidz2) Then years down the line I will either replace the 6x4TB drives for 6x6TB drives or add another vdev.