This isn't going to work: 1) The PERC 6 will NOT take 3TB drives; the max size is 2TB. 2) You cannot remove disks from an array - your 5x1TB RAID 5 must always have 5 or more disks (you can add but not remove).  Even using the same number of disks, is it not possible to make the array/VD smaller. 3) Even if you used 2TB disks, there is no way to make the RAID 5 bigger using the additional space on the disks - with 5 disks in RAID 5, it will remain the same size. The only thing you can do with the new space is create a second RAID array across the disks (called 'slicing').  This new VD will be handled by the OS as a separate 'disk'. Keep in mind if backing up and restoring to a larger array, that if the VD ('disk') is larger than 2TB, the 'disk' MUST first be converted to GPT, and UEFI enabled as the boot mode (instead of BIOS).  Be sure your backup software is capable of restoring a BIOS-based install to a UEFI system (and MBR 'disk' to GPT 'disk').  
I have a R710 with a PERC 6/i, running Win 2008 R2. I have a small drive for the OS, the the other 5 bays are full with 1 TB drives in a RAID-5 array. I need to add more storage, so I want to buy three 3TB drives. I plan on removing one old drives and then putting in the new, larger one. I'm assuming it will take 1 of the 3 TB and repair. Leaving 2 TB free on the disk. I will repeat this step two more times, which will result in three 3TB drives with 6 TB of free space not used in the RAID. Is it possible to have the controller expand storage in my existing RAID-5 array to the free space,  and then remove the two remaining 1TB drives from the array? Does that make sense? Is this even possible? Or am I going to have to backup the data onto another storage device and remove the array and just start a new one with the three 3TB drives and copy the data back?
Swapping to larger drives, but going down two, possible to remove them from 
array and then expand?