The Disk Management utility in new generation Windows can be used to show us the partition style a hard drive has been configured with. In our example below we have more than one drive and only the second drive is GPT. When you open Disk Management there is no immediate clue to this fact and no obvious difference between the two styles of hard drives.

Fig: 1

If you right click in the gray area to the left of the bar graphic for a drive you will receive a popup menu. The list of options here can vary across Windows versions and editions but the option we have highlighted should be present in all Windows-7/8 and some editions of Vista. The option will say the opposite to what the drive currently is, so if as in our example it reads MBR then the disk is presently configured to be GPT, (the option will be grayed out if there are existing partitions on the drive as only unpartitioned disks can be converted).

Whether the convert to MBR/GPT option is present or not, clicking the Properties option will open a dialog box called Device Properties (fig:2) where if you select the Volumes tab you will see specific details of the selected hard drive with the Partition Style clearly listed as GUID Partition Table (GPT) or the alternative Master Boot Record (MBR).

Fig: 2

Note that 32-bit XP never had any support for GPT and will incorrectly show them as being MBR. You can also get to this Device Properties dialog box through Device Manager, where you select the Disk Drive you want to look at and right-click on it and select Properties and when on the Volumes tab press the extra Populate button.

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Fig:3

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Fig: 4

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Only the 64-bit version of Windows XP can fully recognize and work with a GPT configured hard drive. The Disk Management utility will report the same as the one in Vista, but the 32-bit XP can do no more than inform us that we have a GPT drive by detecting the presence of what is called a GPT Protective Partition. This partition that appears to span the entire drive is really just a phantom that has been defined in a dummy MBR partition table that is the only thing retained on the first sector of the drive for the sole purpose of trying to prevent an MBR partitioning tool that knows nothing of GPT from overwriting existing GUID partitions.

Fig: 5

The Disk Management tool in 32-bit XP is GPT aware enough to recognize the protective partition but is not capable of creating or working with GPT partitions or drives and therefore will not allow any tampering with a GPT drive.

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Most of the actively maintained third-party partitioning tools out there are now fully GPT aware and capable, but there are still some that are only aware enough to recognize the existence of the protective partition and so block any messing with a GPT styled drive. There are of course numerous older tools still available and in use that know nothing of GPT or protective partitions and so could unwittingly be used to destroy data on a GPT drive. Such tools will happily let you delete the protective partition and create MBR partitions over the top of the existing GPT partitions, thereby corrupting those partitions and their data. Below are screenshots from a few GPT capable partitioning tools.

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