Z77 ASRock MB ICH10R RAID 01 MIRROR 2x 3TB Seagate HDD reports 2 individual drives of 750GB not 1 Mirror of 3TB in Acronis Disk Director 2011, Windows 7 and Windows 8 Professional. If I format each drive in Acronis as a Basic GPT I can see 2 x 3TB drives. I have the latest firmware on MB and HDD. The BIOS is UEFI. These are data drives not boot.
You mentioned Seagate hard drives are reported as 750GB instead of 3TB RAID mirror. Correct?
Where do you see 750GB reported? Is this under Option ROM or through Seagate application?
Have you tried updating option ROM? You should have at least version 11.2