It is possible to use HDDs of 6TB but keep in mind the following:
- If the Raid volume is bootable you must have UEFI enabled on the BIOS.
- Make sure Chipset mode is set as RAID so the option ROM or CTRL-I is enabled when booting up.
I also would like to know what is the computer brand and model so I can provide more troubleshooting steps.
- The 6 TB disks didn't end up bootable, I installed Server 2008 on a separate SSD.
- When I set the chipset mode to RAID, no Option ROM/Ctrl+I screen is shown. That is the problem here. With other drives that works as expected.
As for the computer model, it's a CEF-Quantum2 (disclaimer: I work for the company that makes those). The CPU card used is a ROBO-8110VG2AR as I told above. There's a further problem about testing this: I already had to send the computer away and I don't have any identical or even similar disks left. I ended up using Windows' own RAID function for the WD drives.
Based on the information you have provided, it seems the system you are using is a server and not a desktop system. If using a desktop solution, when setting Chipset mode as RAID it should enabled the CTRL-I but with the platform you are using my best recommendation is to contact the system manufacture so they can provide the correct functionality and configuration of the device.
Well the chipset on the CPU card is a desktop one (C206), this particular computer just happened to get a Windows Server installed on it :-) Also, this is a configuration issue that precedes the actual installation of the operating system. The same problem would exist even if we tried to install e.g. Windows 7 on it (which we most commonly do, and sometimes even with RAID). Anyway, if we ever have to get larger drives to work in RAID with this CPU card, I'm going to contact the manufacturer of the CPU card. For my purposes we can close this thread.