Server Fault is a question and answer site for system and network administrators. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I installed Windows Server 2008 R2 on a Dell server that has one volume that is a 6 TB RAID 5 array. I created a 120GB install volume and I'm now trying to create a 5 TB data volume. For what ever reason Windows will not allow me to create a new volume out of all of the unalocated space. Windows will allow me to create a new volume out of one 2TB block of unallocated space but not the remaining 3.5 TB block. Tried to post a screen shot but I was blocked.

If I right click on the 1949.85 GB block of space there is the option to create a new volume. If I click on the 3539.5 GB block of space that option is grayed out. If I go into diskpart and try to create a new partition, diskpart says that there is only 1949GBs free on the volume.

I know this process works because I did the exact same thing on another server that we have that is the exact same hardware configuration on which I used the exact same Server 2008 R2 install image.

Any help would be greatly appreciated.


share|improve this question
I did a little more research on the server and I installed a 3rd party partition application. When I try to create a new partition on the unallocated space it tells me that "The disk uses MBR format, the disk space beyond 2TB will be unusable." I'm assuming that is the problem. Anybody have any concept how to fix that? I'd rather not start from scratch and reconfigure the server since I've installed applications and server roles. – natediggs Apr 19 '12 at 15:11
Does your server use EFI? You cannot boot from a GPT disk if it does not - which is likely why the Windows installer decided to use MBR despite the disk's size. – Shane Madden Apr 19 '12 at 18:04
This'll give you the skinny on what Windows is looking for: – JohnThePro Apr 19 '12 at 22:07

3 ways:

  • Go with GPT. As Shane said, it's your boot volume, so you need EFI bios to do that.
  • Do the raid differently (2 volumes), so windows will see 1 disk for system, and 1 for data. So will be able to use GPT for data (if no EFI bios).
  • Convert to dynamic disk. Create 3 partitions of 2TB and make that an aggregate. Never tested and it's ugly. Only try that if the others solutions are really not possible.
share|improve this answer
Pretty sure the third won't work - the underlying problem is the MBR, not the partition size. – MikeyB Oct 23 '12 at 16:09
Indeed, as @MikeyB pointed out MBR is limited to 2TB per disk size, not per partition. The third option will not work with standard MBR. – mprill Dec 24 '12 at 22:15

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.