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Cannot use drives >2Tb in Server 2008 R2

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Last Modified: 2014-02-07
I have an Asus Motherboard with 6 x 3Tb SATA drives connected and onboard RAID enabled. 4 drives are RAID 10 = 6Tb and 2 drives are RAID 1=3Tb

In Disk Management I cannot seem to do anything with the larger drive as it has all options greyed out.

Disk 0 (5589Gb) has 100Mb System Reserved partition, 2047Gb unallocated and 3541Gb unallocated.

Disk 1 (2794) has 2058Gb Drive C: and 746Gb unallocated.

If i right click on the Disk label Disk 0 I just get properties and help, everything else is greyed out. On the disk 0, 2047 partition I only have the option to create a new simple volume, which if i do then once formatted i dont have the option to extend the volume, it appears i can do nothing with the 3541Gb partition at all.

Again, if I right click on the Disk 1 label everything is greyed out, and if i try and extend the C: drive it appears to work and then gives the error message:  "Only the first 2Tb are usable on large MBR disks. Cannot create partitions beyond the 2Tb mark, nor convert the disk to dynamic."

I'd like each disk to use the whole partition but cannot work out how to.

I tried using partition magic but got the error that the drives are unsupported when i open it up, i assume this is because theyre using the RAID controller on the motherboard, or they are simply too big for that too.

As i'm wanting to backup some very large VMDK files I need to make use of all the space so need to come up with a solution.
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Model numbers of those drives.
Do not use hardware RAID if they are not RAID certified(WD RE4's ,Seagate ES)

On cheap (non server) MOBO,using the onboard RAID is just asking for trouble.
They are unreliable.

The MOBO ,if you intend to have partitions greater than 2.2 TB and want to be able to boot,MUST be UEFI enabled.
No UEFI,no big volumes.

You must also have formatted those partitions using GPT,no MBR.

I believe you need the 64 bit version of 2008 also if you need to be able to boot those >2.2 TB volumes.

32 bit can read and write them,just not boot them.
Top Expert 2010
Bottom line
1. Do NOT use fakeraid motherboard RAID. It is crap. Use native windows RAID.
2. Unless you have a UEFI BIOS, and 64-bit Windows 2K8 or higher, then the largest physical drive you can have for the disk you want to boot is 2TB.  There is a way around it, but it means reprogramming the HDD to pretend to be a 2TB drive, and that is something you typically pay somebody to do, as it requires some specialized software.   (My company does this, but it costs more than you probably want to pay due to the hassle of shipping the disks and time).

Or, Get a premium RAID controller that lets you define multiple target LUNs in a RAID1 set but that will cost more than just buying a pair of 2TB drives.


The drives are Seagate 7200.14 3TB SATA III 3.5", model: ST3000DM001, which I assume are not RAID certified as they are just cheap drives, I didn't realise there was such a thing.

Windows is 64-bit and BIOS is UEFI (but i need to check if it is enabled). Motherboard is an ASUS Z87-PRO.

If you think I should remove the MOBO array and create one in Windows I guess thats a complete re-install (it took half a day to get all the updates!) unless i can do a backup... i'll check. Having never done it before I'm not sure how you do it if the OS is going to be installed on there too, and would it let me use all 6 drives in RAID 10 do you know?

Many thanks
Distinguished Expert 2019
Without a 3rd party partition tool you can't convert the current installation to GPT without data loss and even some that do convert without data loss won't let it boot any more.

Windows software RAID does not do RAID 10 at all, and although it does support RAID 5 it can't boot from it because the driver that deals with the algorithm isn't loaded until it's booted. It supports and boots from software RAID 1 because all the initial reading during boot comes from one disk.

You can't get a hold of a copy of server 2012 or W8.1 can you?

It uses REFS : http://en.wikipedia.org/wiki/ReFS


and if you set up those cheap disks using that,you will probably have enough ECC to allow you to use them as an alternative to HW RAID.

You can then just set them up as iSCSI targets for the VMDK files .