Optiplex 790: only 2TB of 3TB drive visible

Posted on 2013-01-26
Medium Priority
Last Modified: 2016-11-23
I put a 3TB drive (a WD30EZRX) in my Dell 790. In Disk Management, all I can format is 2048GB. The rest of it is marked as "746.52GB Unallocated".

The 2048GB partition says "Healthy (Active, Primary Partition)". When I right mouse on the 746.52 GB partition, there are no options except Properties.

Two questions:

1. How can I set it up so that I can use all of the space on the HDD?
2. Is there any way to use all free space on the drive as one 2.8TB drive?

Thanks very much,

Question by:243johnm
LVL 100

Expert Comment

by:John Hurst
ID: 38822917
There is probably a BIOS limitation on the size of the hard drive and so it is unlikely you can use all the space as one partition.

Try making a new partition of the excess space. You may need to use a partition manager tool to do this. As an example, look at http://partition-manager.com/

.... Thinkpads_User
LVL 88

Accepted Solution

rindi earned 2000 total points
ID: 38822924
What OS are you using? Is this the OS drive, or a 2nd drive?

For one thing, a disk has to use GPT in order to get more than 2TB available. Traditional MBR initialized disks are limited to 2TB max.

If it is the 2nd disk and you aren't booting from it, you should be able use disk management to convert it to GPT, but as far as I know it must be empty for that. After that you can partition it and you should have all space available to it.

If you are using a 32 bit version of Windows 7, and you want this to be the disk with the OS on, you can only use MBR and are therefore left with 2TB.

If you are using a 64 bit version of Windows 7, and your mainboard uses a modern UEFI BIOS, you can set the disk to GPT and install Windows 7 on it, and you should then also have the full capacity available. If you don't have a UEFI BIOS, you will only be able to install Windows to an MBR disk and then you will also only be able to get 2TB out of it.
LVL 34

Expert Comment

ID: 38822993
"1. How can I set it up so that I can use all of the space on the HDD?"

It seems your OS is limited to 2TB
You need to partition your Hard Drive so that the OS is on ( C partition ) and storage on ( D partition )
That way you can put the OS on a small ( C partition of say 500GB ) and have the remaining space of 2.3TB as ( D partition for storage )

You will need a partition software such as:
Partition Manager 12 Free Edition

"2. Is there any way to use all free space on the drive as one 2.8TB drive?"
Not with your present 2TB limited OS

You can also partition the drive before you install the OS using this free software:
LVL 97

Expert Comment

by:Lee W, MVP
ID: 38823026
As rindi stated, this is a problem with MBR.  If the system is not configured as a UEFI system it will not create GPT drives by default and CANNOT boot from GPT drives.  If this is the ONLY drive in the system then you won't be able to access the entire drive unless there's a BIOS setting to switch to UEFI and then you can re-load Windows.  Otherwise, you CAN make this a "secondary" drive that will be fully seen by making it a GPT disk and NOT an MBR disk - you CANNOT convert, you remove all partitions and make it GPT.  Then you partition it.

If you want more understanding, google GPT disk.

Author Comment

ID: 38823079
Thanks all. First off, this is a 2nd drive, the original boot drive has not been replaced...

I took a look in the BIOS and there was no way to change to GPT there!

In Win 7 Computer Management > Storage > Disk Management, I de-allocated the volume and returned it back to virgin state. I was then able to set it up as a GPT drive (I had chosen MBR first time around). After formatting, I now have 2.72TB of free space!

Prior to adding this drive, we had a tape backup of the system and data partitions of our server as well as offsite backup of the data on our server. I will now be able to setup sync of the data partitions from the server to this drive, and improve management of the offsite backup...

Thanks again,


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