External HDD (MBR) has partitions larger than 2TB

[spandexninja]

I have a 2.5TB external HDD from WD and a 3TB external from Seagate, and I just assumed that they were formatted in GPT since they come with a single partition (larger than the 2TB MBR limit). However, I checked in disk management today and these drives are actually MBR.

After using diskpart /clean on the external drives, I am no longer able to make partitions larger than 2TB in MBR (GPT can do it fine).

How do MBR external drives come with partitions larger than 2TB?

 

[BFG10K]

The enclosures likely employ some kind of emulation/driver layer. Are the HDDs still inside them?

 

[imagoon]

3TB seagates emulate 4k sectors via USB. This lets XP see it as a 3TB drive. It has side problem of causing apps that don't quite "get" 4k sectors to fail. VMWare Workstation and Windows Backup being 2 that I can think of right off the bat.

Edit...

The 2TB limit is based on addressing 512 byte sectors. Whatever 2TB / 512 bytes = max about of logical blocks that can be allocated. If you increase the sector size to 4k you could use MBR to address 16TB drives.

 

[spandexninja]

Interesting... wish I had knew that when I bought it so I could have changed it to GPT right away.

Thanks for the info.

 

[imagoon]

Interesting... wish I had knew that when I bought it so I could have changed it to GPT right away.

Thanks for the info.

Formatting to GPT doesn't fix the 4k issues though.