Rapid Storage kept pestering me after I installed my newest 2 TB SSD to create a volume and I saw no harm in it at the time, so I did. For some reason instead of a 3 TB volume in disk management I am shown a 2TB Disk with 1 TB worth of unallocated space?!? Perhaps I'm going about this wrong as I've never used Rapid Storage until now, but am I just being stupid or what?
If you delete the 2TB volume that currently exists within the array, you should then be able to create a 3TB volume. Alternatively, you can just create a 1TB volume from the free space and then have two separate drives (2TB and 1TB).