I believe i understand what you're getting at now.  You not wanting to RAID the other two 2TB drives. So, what you're seeing is correct. The OS won't show the other drives because they must be setup as RAID If they are connected as such.  You'll need to create them both individually as two separate RAID 0 VD's. You'll then see 3 VD's total from the PERC RAID BIOS.  VD0- OS RAID1 (Drives 0 & 1)VD1- RAID 0 (drive 2)VD2- RAID 0 (drive 3) Within Windows Disk Management, you'll also them as 3 separate logical drives that you can work with. 
Hi, I am a bit new to RAID configuration. I have 4 SATA HDDs, 2 1TB HDD and 2 2TB HDD. I only want to have my 1TB on a RAID 1. When I did that, I could not find the 2x 2TB HDD. Is it possible to access the other 2 HDD when they are connected to one controller?
Dell PowerEdgh R420 and PERC H710 mini RAID Set-up