2TB Limit with Server 2008 R2 X64 Raid 5 Array

Server Specs:
IBM x3620 M3 with 8x 2TB SAS drives with a ServeRAID M5015 SAS/SATA Controller.

Earlier this week I had configured a RAID 5 array using the LSI MegaRaid config wizard in the bios. I used all 8 drives in a  RAID 5 volume.

I then preceded to install Windows Server 2008 R2 x64 onto that array. When I booted into the Operating System - I shrunk the C:/ drive from 12.53 TB to 100 GB and then used the remaning space as a Backup Drive (V:). Everything was working fine.

Today i had a change of plans and decided to create 2 RAID 5 arrays (each with 4x2tb drives).

I then attempted to install Windows Server 2008 R2 x64 onto the first array. Once i entered into the OS i noticed that i only had access to 1.99 TB of data. The rest of my array was unusable and unavailable. I could not extend/expand the array - or create new volumes with it.

The send new 4x2tb array that i created was not the OS drive - and i was able to convert that to a dynamic/GPT disk so that all of the 5.5TB was usable.

MY QUESTION: Why am i now limited by the 2TB limit? I do not think that i did anything different with the setup this time. I am confused because earlier this week I had server 2008 R2 x 64 using the entire 12.5 TB array with (8x2TB) drives - now, using the same drives - just in different arrays - i am only able to access 2Tbs.

Any ideas?

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DavidConnect With a Mentor PresidentCommented:
The constraint was always there ... MSFT does not support bootable disk > 2.09TB unless you have an itanium-based system (or UEFI).  The difference is BOOTABLE.
PowerEdgeTechIT ConsultantCommented:
Server 2008, 2008R2, Vista, 7 cannot boot to a larger than ~2TB volume unless installed on UEFI-enabled system.
RavenIndAuthor Commented:
How was it that i had it booted before than? I was booting to a 12.5 TB Drive on a 100GB partition... I do also remember there being a EFI System partion or something along those lines with the first install...
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I object closing for zero. His question was asked, and answered by two experts correctly.  I will add that an array, volume, and partition are different things.  Booting to a 100GB partition is different then booting to a volume or disk.  To make it easier to understand, let me just say that windows won't let you boot to a C: drive that is > 2.09 TB. the 100GB partition is C:, so it worked. In light of the additional info, author clearly tried to make the 4x2GB array into a "C" drive.  This will not work.
PowerEdgeTechConnect With a Mentor IT ConsultantCommented:
Agreed.  I thought that by pointing out the boot partition size limit, that it would be apparent to you why the first install worked and the second did not, because the with the first one, you created a 100GB partition, which is fine, and the second install only saw 1.99TB for the C partition, because that is all it can handle (non-EFI).
PowerEdgeTechIT ConsultantCommented:
I think splitting the points would have been more appropriate, but thank you for not simply closing the question.
thx everybody.
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