question

Hi,

Thank you for posting your issue to Microsoft Q&A forum.

Have you retried to reformat the drive to see if it fixes the problem?

For more solutions, please kindly check below similar thread.

External USB Drive not recognized for backup

Best regards,

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Definitive information was not found for server 2016 however these are some known problems as of 03/23/2022:

Known issues or limitations

Because the transition to a single-disk capacity of greater than 2 TB has occurred fairly recently, Microsoft has investigated how Windows supports these large disks.

The results reveal several issues that apply to all versions of Windows earlier than and including Windows 7 with Service Pack 1 and Windows Server 2008 R2 with Service Pack 1.

To this point, the following incorrect behavior is known to occur when Windows handles single-disk storage capacity of greater than 2 TB:

The numeric capacity beyond 2 TB overflows. It results in the system being able to address only the capacity beyond 2 TB.

For example, on a 3-TB disk, the available capacity may be only 1 TB.

The numeric capacity beyond 2 TB is truncated. It results in no more than 2 TB of addressable space.

For example, on a 3-TB disk, the available capacity may be only 2 TB.

The storage device isn't detected correctly.

In this case, it isn't displayed in either the Device Manager or Disk Management windows.

Many storage controller manufacturers offer updated drivers that provide support for storage capacities of more than 2 TB.

Contact your storage controller manufacturer or OEM to determine what downloadable support is available for single-disk capacities that are greater than 2 TB.

https://docs.microsoft.com/en-us/troubleshoot/windows-server/backup-and-storage/support-for-hard-disks-exceeding-2-tb

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Thank you everyone for the comments. I have tried as suggested and made sure the drive was formatted to NTFS standards but I am unfortunately still unable to resolve the issue. It seems to detect the drive as normal when making a one-time backup. But it doesn't show in the list of available drives when creating an automatic backup schedule. I have also tried to split the drive and have 2 (5TB) partitions, but still the issue was unresolved.

I will continue to experiment and see what I can do.

All,

I was able to resolve my issue. I spent some time this morning going over some settings and such. The external drive came with partition style GPT by default. I formatted the drive to NTFS and changed from GPT to MBR. Once I did that, Server Backup was able to see it in its entirety too (9TB). Now I have successfully created an automatic backup schedule. Thank you everyone for being willing to assist.

If you're willing to test the drive for academic purposes please comment into this thread.

Please convert from MBR to GPT and see if it still works properly.

I should have another drive shortly and I will test once I have it. I would also like to know if it will work afterwards.