With RAID, the controller takes the disks and creates a "logical" disk, and that is all that is presented to the OS.  So, if you create a 2x3TB RAID 1, the logical disk is 3TB, and the OS knows nothing of how many disks makes up that logical disk.  Windows wouldn't know the difference between a 2x2TB RAID 1 and an 8x500GB RAID 10.  The only way you can see/monitor/manage the individual disks that make up the array is to install software capable of interfacing with the controller (Intel's RAID storage manager, and possibly Dell's OMSA, which usually can only see Dell rebranded controllers (S-series, H-series)).
Hello, I've installed Windows 2012 Essentials on a Dell T20, have 500GB hard drive for OS, and 2x 3TB hard drives in Raid 1 array.   Did raid setup through Intel Rapid Storage Controller with 2x 3TB hard drives, can see them both on the Ctrl-I setup, but once in Windows Server Essentials Dashboard, I only see one hard drive, and cannot set up Backup. I maybe missing understanding how the Raid setup is applied, but would expect there to be some kind of monitoring of the mirroring that should be occurring.   Can someone confirm the setup process, and how I should be reviewing it? Thank you for your replies.
New Install T20 with 2012 Essentials-Raid 1