2TB storage Limit Windows 2012 R2 on Intel Raid Card

We just go an Intel Server with 8 Drives and a PCI raid card with 1GB memory on the raid card. I did a Raid 6 with a total 8 drives ( 4TB each) . I installed  Windows on the raid 6 volume that I created using the RAID bios. When the install finished and I logged in . I see a 2 TB partition which windows is on and then I see a 20TB unallocated space. Please see the attached image. What do I need to do to make the space usable. I was hoping to have two partitions on this volume since I was going to install Hyper-v and have two vm running  and one  being a file server with 12 TB of files on it. Someone suggested that this happened because I marked the volum as MBR when creating the RAID volum in the raid bois.  ( yes, I did that) . When I go back in the bios , there is nothing there to remove that or change anything .  I have attached some pictures. It seems like I could just extend the 2TB drive to the empty space, but I am not sure.  

Disk Config
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netcompAsked:
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Cliff GaliherCommented:
You have to know what your RAID controller supports and you have to understand windows. This link covers windows support for drives larger that 2TB, but as you didn't give any information about your raid controller beyond "Intel" we can't provide more information there,

http://support.microsoft.com/kb/2581408
rindiCommented:
You either need to set the BIOS to UEFI so you can make a GPT disk from your Array. Only with an UEFI BIOS and a GPT disk can you boot to a volume that allows you to use more than 2 TB. If you do that you will have to install the OS again.

Most RAID controllers though allow you to split an array in at least 2 Volumes. Then you can create a very small volume for your OS (2012r2 fits nicely onto less than 30 GB), and another Volume with the rest of your array. You can then use the first volume as a traditional MBR disk and install the OS without needing an UEFI BIOS and it higher complexity, and the other Volume you can setup as a GPT disk and use that for data. That disk, as it is GPT, supports more than 2 TB, so you can use all it's size.

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Gary CaseRetiredCommented:
r.e. Cliff's comment ==>  There's no issue with drive support -- the total amount of space is consistent with the drives that are installed.

Why Disk Management doesn't allow you to create a 2nd volume is another story.   I suspect it is indeed because you "... marked the volum as MBR ...".     Since there's no means in the RAID controller to change that, you likely need to simply delete the entire RAID array and recreate it -- either reinstalling Windows, or imaging it first; then recreating the RAID volume, and then restoring the image to the new logical disk].

I assume that if you right-click on C:  you also don't get the opportunity to "Extend Volume" ... is that correct?
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Gary CaseRetiredCommented:
As Rindi noted, if you re-do the RAID array, you may need to make two logical drives, so one can be MBR if you don't have a UEFI BIOS.    If you have a UEFI BIOS a single large GPT drive is fine.
netcompAuthor Commented:
Graycase and Rindi,
I have an intel Rs25AB080 Raid card. I think by setting UEFI in the bios , you are talking about the RAID card bios and not the server's bios? Correct? , If so, in the RAID bios ( raid utility ctrl+ G during boot) , I do not see a UEFI option or can't find it.

Cliff, I appreciate your help in this post and the other post about hyper-v from earlier today, but going forward, please do not respond to my questions if your response is going to be " You need to know more, Understand x,y,x, and give more info" . Thank you,
Cliff GaliherCommented:
So we (not just me, but all experts, are supposed to psychically know if your RAID controller supports 512e or native 4k disks? Or if your computer has UEFI support? Because both of those factors *FUNDAMENTALLY* change how you fix your problem. But hey, I guess you want free easy help with no effort while attacking those providing assistance. Good luck with that!
rindiCommented:
No, not the RAID BIOS. This is part of the PC's BIOS. Personally though I don't think using that is worth it, as you always put the OS on a small disk/partition anyway, so it can be an MBR disk. As long as you can split your RAID array into multiple volumes I'd do that.
David Johnson, CD, MVPOwnerCommented:
if you have a uefi bios (motherboard) when you select the boot options  you will see two dvd's one is marked EFI that is the one you MUST use for drive support >2TB

If you don't want to rebuild your raid and you've booted into the EFI version of setup.. press shift-f10 which will bring up a command prompt
diskpart
list disk
select disk #  (replace # with the # of your disk)
clean  
exit
exit
now continue the os installation.
netcompAuthor Commented:
Good News. The Intel server had option that came to my aid . If you hit f6 during post, you get the boot options and one of those options is UEFI boot. When you do that , it will install the OS on a GPT partition. Or you can do Shift + f10 and use command line during install and convert the disk to GPT.  Now I have a disk with 22TB.
Now I plan to Install hyper-v and setup a VM that will be the file server that will hold around 14TB of data and growing.
What would be the best way to do do this considering backup and snapshots? Should I leave this 22TB as it is or should I create two partitions.

Also, should I create a VM and then once the VM is created create separate virtual disk to hold the DATA for the file server VM. So, that I would have a C; drive(os)  and D: (files) drive within the file server vm?  

Thank you,
David Johnson, CD, MVPOwnerCommented:
1 partition for the o/s and 1 more or many more for data (which includes the virtual machines)
With a gpt disk you can create unlimited primary partitions (not limited to 4)
netcompAuthor Commented:
David,
Within the fileserver VM which will hold 14TB data, should I have a C: drive ( os) and create another virtual disk for D: for the data? or should the vm data and the files be on the same drive?I wonder if there is  a difference. ? Thank you,
David Johnson, CD, MVPOwnerCommented:
my best practice is to always separate the o/s and data
Philip ElderTechnical Architect - HA/Compute/StorageCommented:
Got bit by this once.

Create your array with two logical disks. We use 75 GB for the OS and the balance for the VM files.

RAID 6.
Gary CaseRetiredCommented:
Agree -- if you separate the OS and data in the VM, you can easily "image" the VM at any point in time by simply backing up the virtual hard drive with the OS.

Cliff:  r.e. "... So we ... are supposed to ,,, know if your RAID controller supports ..." the 4TB disks that were installed. ==> Yes, by simply looking at the picture in Disk Management it was clear that disk size wasn't the issue.   No knowledge of the specific controller needed.       A RAID-6 with 8 disks will clearly have 4 x 6 = 24TB of space, which is exactly what's shown.   [22351.74 GB (in "computerese" x 1.024 x 1.024 x 1.024 = 24,000,000,000,000 bytes]
rindiCommented:
I always prefer a small RAID Volume for the OS only disk, and another RAID Volume for the rest, Rather than partitioning your RAID Volume (The OS should see 2 separate virtual "Disks", and not one virtual "Disk" with several partitions.
andyalderSaggar maker's framemakerCommented:
Cliff's post was exactly what I would have posted, the link he gave is about "drives" as Windows sees them, i.e. virtual/logical drives as presented by the RAID controller and how to use GPT disks with UEFI.

Not until we knew it was a Rs25AB080 we did not know that it does allow multiple virtual disks on a single drive group. You can't expect him to guess it's a re-badged LSI controller without telling him what card it was.
netcompAuthor Commented:
David's solution was the one that allowed me to install the OS. Thank you all for your inputs.
Philip ElderTechnical Architect - HA/Compute/StorageCommented:
There is a catch. Set up the disk structure at the RAID BIOS level with two logical disks and one can install Windows into an MBR based partition.

Set up using GPT and uEFI means backup becomes a question mark. Not all vendors support restore to uEFI/GPT at this time.
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Windows Server 2012

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