Question Single drive is seen as two separate physical disks. How to reset?

Jun 20, 2019
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Hi,

I have a single 4TB drive that was once part of a storage pool (a two disk mirror) in Windows 10.

I want to reuse the drive but when connected it is showing as two separate physical disks under disk management. One is 2TB the other is 1.639TB. Both Basic GPT.

How do I reset the disc to a single 4TB?

I've not seen this happen before where one physical drive with two separate partitions is seen as two physical drives. Any idea what’s going on here?

Thanks.

B R
 

popatim

Titan
Moderator
If you need the data then you have to copy it off to another drive. Delete both partitions and then create one new big one.
You use disk management to do this.

If you don't need the data then skip the copy step.
 
Jun 20, 2019
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If you need the data then you have to copy it off to another drive. Delete both partitions and then create one new big one.
You use disk management to do this.

If you don't need the data then skip the copy step.
Dont need any data. Thanks for the suggestion. Ive tried that and without any formatted partitions it still appears as two separate physical drives with unallocated space.
 
Jun 20, 2019
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I wish you would have said this was a usb drive. Which exact one please.
On Some drives this was a function of the sata>usb bridgeboard and needed a special utility to rectify.
Its not a usb drive. I have temporarily connected it (a Western Digital Red Label 4TB - WD40EFRX as described above) via a USB/SATA adatptor as I have no free SATA ports. Sorry for the confusion.
 
Seagate's OEM version of Acronis TrueImage (DiscWizard) would set up a 2TiB+ HDD in this way. I believe WD also supplied an OEM version of Acronis.

The user would partition the drive as a 2TiB physical drive with an MBR partition, then DiscWizard would create a "virtual physical drive" from the remaining disk space, also with an MBR partition. However, one would need to install Acronis's driver in order to see the virtual drive. The partition table for the virtual drive would exist at the 2TiB boundary, so the 4TB user area would look as if two physical drives had been glued together at the 2TiB point.

But you say that your partitions are GPT, not MBR …

You might like to examine the 4TB drive with a disc editor, eg DMDE.

https://dmde.com/

Examine the area around sector 4294967296. That's the first sector beyond 2TiB.
 
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Jun 20, 2019
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Hi Everyone,

Just an update in case anyone comes across this issue.

I had the drive connected via a SATA to USB adaptor. Once I had freed up an internal SATA port and could connect it directly the drive was then visible as a single drive.

This revealed a limitation of the USB bridge that I was unaware of.

Cheers.
 
Jun 20, 2019
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Seagate's OEM version of Acronis TrueImage (DiscWizard) would set up a 2TiB+ HDD in this way. I believe WD also supplied an OEM version of Acronis.
Thanks for the info. Actually I have the full versions of Acronis TI and Disk Director but neither were of any help in this case.

I have subsequently found that the problem was because I had the drive connected via a SATA/USB adaptor. Once I was able to free up a SATA port and connect the drive directly it shows up as one drive.

Cheers.
 

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