"I anticipated using 500GB each from the two added drives for Virtual Disk 2.  Then I planned to use the remaining 1.5TB from the drives as Virtual Disk 3 in a RAID-1 array.  I have done this with other PE servers in the past." This has only been allowable on a VERY small number of controllers found in Dell servers.  Regardless, you cannot do that on a PERC 6.  You could replace your 3 existing drives with 2TB drives, then create a second (6TB) array across the disks (ALL disks in a disk group must have available space, and you can't replace drives with bigger ones and expand the existing RAID array size).
Hello, We have a PE T610 with a PERC 6i controller. Virtual disk 1 : 2 x SATA 250GB in a RAID-1 Virual disk 2 : 3 x SATA 500GB in a RAID-5  We added 3 additional 2TB drives to the server.  One drive was designated as a Global Hot Spare.  The other two drives were added to the RAID-5 array. I anticipated using 500GB each from the two added drives for Virtual Disk 2.  Then I planned to use the remaining 1.5TB from the drives as Virtual Disk 3 in a RAID-1 array.  I have done this with other PE servers in the past. But, after the 500GB is used from each of the disks, I cannot used the remaining unused space.  It shows the "Available RAID Disk Space" as 0.00GB. Why isn't the remaining space on these drives available for me to use? Thanks for any and all help on this. Bryan Hunt 
PE T610 - Perc 6i - Odd state after adding additional drives