Hard Disk and Ready NAS 1500

You have an X86 (OS 4.2) system.  The HCL hasn't been updated for years, but it does include 3 TB models.

 

In general, you can use larger disks still (either NAS-purposed or enterprise class).  There are some limits to expansion:

• volume size can't grow larger than 16 TiB
• volume size can't grow more than 8 TiB from it's starting size.

 

Both of these are on the volume size, not the disk capacity.

 

So if you started 4x1TB using XRAID, you have a 3 TB volume - which can grow to about 11.7 TB.  4x3TB would give you a 9 TB volume, which is fine.  But 4x4TB would expand to 12 TB, which is over the ceiling for that starting point.

 

The solution is to do a fresh factory install, with the new disks in place.  If the disks are the same size, you could even use 4x6TB (though they aren't on the HCL).  The volume size would be 18 TB - over the 16 TiB.  But you aren't growing larger than 16 TiB, you are creating a volume from scratch.