Q. I've installed a 3TB drive in my Windows server or client machine and it's not working correctly. Why not?

A. The first thing to check is the bytes per sector of the volume created on the disk, as explained in FAQ "Q. How can I check how many bytes per sector my NTFS volume uses?" The likely result will be that it reports 4096 as the bytes per sector, which isn't currently supported by Windows, per this Microsoft document and this one. While it may be possible to store files on these drives, you will be unable to mount a Virtual Hard Disk (VHD) on them—which means Hyper-V can't use them to store VHDs and you won't be able to perform Windows Backups to the device (which write to mounted VHDs).

To use a drive that has a physical 4KB sector size, you need it to logically expose a 512 byte emulated sector size (known as 512e). The firmware in the drive takes care of any conversion operations. If you see 4096 as the bytes per sector, contact your disk supplier, because they might have some firmware update or configuration to make the disk appear as a 512 byte emulated sector size.

This problem is being reported mostly on USB-connected drives, where the USB bridge actually reports itself as native 4KB sector size. If you removed the disks from the USB enclosure and directly connected them via SATA, they would likely be using the 512 byte emulation and therefore be fully usable. I'm not suggesting you do this—it would probably destroy your warranty.