Configure New External Hard drive for Windows Server Backups

To make a new external disk usable for Windows Server Backup (WSB), it must be in a compatible format and not contain extra system partitions like EFI System or exFAT. WSB generally prefers NTFS and a clean, MBR or GPT disk without boot partitions.

When performing this, proceed with caution. Make sure you have the correct DISK # and that you have confirmed it multiple times. You can confirm the DISK # by viewing Disk Management tools to be sure it is the correct External.

Powershell

1. Open PowerShell as Administrator

• Right-click Start → Windows PowerShell (Admin)
  

2. Confirm Disk # is the external drive

Run:

Get-Disk

Make sure:

• Disk # matches
• ~xxxx GB size matches
• Online

3. Wipe Disk # clean (removes EFI + exFAT)

This immediately removes all partitions from Disk #.
(Be sure to replace # with the correct Disk number.)

Clear-Disk -Number # -RemoveData -Confirm:$false

4. Reinitialize Disk #

GPT is recommended:

Initialize-Disk -Number # -PartitionStyle GPT

5. Create a new NTFS partition for Windows Server Backup

Be sure to replace the backup label name with the correct information for: 2025_11_21_Client_BackupDisk through the format of YYYY-MM-DD_ClientName_BackupDisk.

New-Partition -DiskNumber # -UseMaximumSize -AssignDriveLetter |
    Format-Volume -FileSystem NTFS -NewFileSystemLabel "2025_11_21_Client_BackupDisk" -Confirm:$false

After this, Disk # should appear as:

• One NTFS partition
• No EFI system partition
• Fully compatible with Windows Server Backup

Example: