how to setup windows 2012 as GPT to have partition bigger than 2tb


I have a Dell R620 with 3tb of disk on a Raid5.  When I try to install win 2012 .. it does not partition the disk properly.. Essentially I am trying to give os partitioin 400gb and rest needs to be on a single partition of 2.6TB.  I know its an issue with GPT.. I am not sure how to configure it so when I boot off the usb drive win 2012 setup installs it as a GPT.  

On the bios I have it setup as uefi.. not sure if it needs to be on bios.
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When you install server os, instead of installing go to repair option and from command prompt and through diskpart utility convert it to gpt disk and then install os
iamaidiotAuthor Commented:
Thanks Mahesh I will try that and update
Are you using live cycle to deploy the OS, make sure you use uefi and not bios type boot.

Raid5 will have a decline in pergormance shoukd one drive die, and a total data loss shoukd a second one fail before the rebuild completes.
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James BunchSystems EngineerCommented:
When you have it converted to GPT, continue through the installation. During the option to standard install, select custom. Here you will see the available disks as well and make sure, if its a new install, that you delete all partitions if any. Then, select the unallocated space. There should be a New option underneath these and here you can select a new partition with the custom size you are looking for. The rest will be unallocated (Which is fine for now) and complete the install.

Once inside Windows, go to your Disk Manager and select the unallocated space and create a simple volume for the remainder and you can do what you need with that repository space.
iamaidiotAuthor Commented:
Hey Mahesh,

So I did as you mentioned.. it says disk converted to gpt.. then I restarted booted of my usb drive again and when I go to install create a os partition i get partition 1 350gb parttion 2 1.7tb  parttion 3  1.3 tb.  I need the 1.7 and 1.3 to be in one partition for a total of 3 tb.. I am installing os anyways to see if I can merge them from os disk management (not sure if that will work tho)
You should partition the disk in hardware via the RAID controller BIOS, just create one 400GB logical disks and have the rest of the space as a second logical disk. Then it doesn't matter if you use UEFI or BIOS because the first disk Windows sees is only 400GB.
Delete those all disks and create only one disk with whatever size you need and install os
Later on from os, u can format rest volume
iamaidiotAuthor Commented:
Hey James,

When I am in UEFI I cant load from usb.. keeps saying retry (even if i choose usb drive to boot from).. so I had to boot from bios and I converted to GPT.. went to install (new install) the entire volume was 3.3 tb.. when i chose to create a custom partition of 350GB then it split into 4 partition one 350mb  one 350gb (os install) and two other partitions of 1.7 and 1.3 tb  (if its already gpt then it should be 3tb right?)  to make sure I went back to diskpart and tried to do convert gpt again and it says that u need to choose a mbr disk which tells me that it was already converted.. So I did the install anyways loaded to os and when i went to disk management i c the 1.7 and 1.3 next to each other but I cant extend the partition to combine it doesn't even let me format the last 1.3 partition..

Just fyi I do have set on raid 5 for 7 disk and 8th is the spare.. its on a dell R620 with per 7 mini controller

thank for your help appreciate it
iamaidiotAuthor Commented:
Mahesh are u saying to install it os on the 3.3 tb .. when I do that the os creates two partitions one for 2tb and rest is 1.3 never letts me combine  3 tb all together.. maybe its an issue because I am having to boot from bios instead of UEFI .. but for some reason it does not boot from usb from uefi...  forgot to mention i am using windows 7 usb tool to burn the iso to usb.. boots fine from bios but not uefi
If you use the PERC BIOS to partition into two logical disks it's much easier, you don't even have to create the second logical disk on the PERC until Windows is installed, then you can create it with Dell's server manager when running Windows. You may also be better off using RAID 6 rather than RAID 5 plus spare, redundancy is better that way although it is a bit slower.
iamaidiotAuthor Commented:
Hey Andy,

I am assuming by logical you mean virtual disk.. Currently I have 8 disks .. if i create two vd then i need 2 for os  raid 1  then 5 for raid 5 and one as global spare.  and I will miss out on some space... I can do that I was just thinking if there is a way around it.. if not then I can do what u suggested
iamaidiotAuthor Commented:
Hey Andy,

I think i might just do that and call it a day.. I would still have to convert the 2nd logical drive into GPT after installing windows right.. should I do that from disk management or dell server manager?
You create one array with two virtual disks on it so you do not lose any space, you create the array and then slice it like a cake. By default it sets the first logical disk to use all the space but you can adjust that down to 300GB or so. Then after installing you use OMSA to create another vd with the rest of the space.
iamaidiotAuthor Commented:
Can i do that from perc h700 mini controller bios or is that only on omsa?  Maybe I dont actually have omsa I will try and download it and try it
In this video at 0:24 when he says "tab over" you can see the VD size option momentarily highlighted. Instead of pressing tab change the VD size to 350GB or whatever value you want at that point.
What idrac type do you have, express ir ent
When deploying, are you using like recycle or build and update boot disk/usb?

When configuring raid, you specify as indicated raid 5 spanning all drives for a total space of 2tb as an example for volume 1, and then once the OS us installed in a partition, and you install server administrator (openmanage server administrator) you can allocate the remaining 1.Tb to volume 2.
iamaidiotAuthor Commented:
thank you for  all the help.. i got it to work by using dvd rather than usb.. for some reason with usb in gpt patitions werent working properly and with mbr partition was splitting.. thanks for taking the time

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