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--- title: Replace a Drive on an Azure File Sync Server description: Learn how to replace a drive on an Azure File Sync server because of hardware decommissioning, optimization, or end of support. author: khdownie ms.service: azure-file-storage ms.topic: how-to ms.date: 08/14/2026 ms.author: kendownie # Customer intent: As a systems administrator, I want to replace a failing drive on an Azure File Sync server, so that I can ensure continued access and optimize storage performance while minimizing downtime for users. --- # Replace a drive on an Azure File Sync server This article explains how to replace an existing drive that hosts one or more Azure File Sync server endpoints, either on an on-premises Windows Server installation or on a virtual machine (VM) in the cloud. This replacement could be because the drive is failing, or because you want to optimize and balance resources by using a different size or type of drive. Some of the steps differ slightly depending on whether your Azure File Sync registered server is located on-premises or in Azure. > [!IMPORTANT] > Replacing a drive always involves some amount of downtime for users. Follow the steps in this article. If you simply re-create the drive and restart the storage sync service without first deleting the server endpoints, the server automatically throws away the sync database. ## Step 1: Create a temporary VM with new server endpoints Create a temporary VM (Server B) that's as close as possible to your registered server (Server A). If your registered server is on-premises, create a VM on-premises. If your registered server is in the cloud, create a VM in the cloud, preferably in the same region as your registered server. Then, [create the server endpoints](file-sync-server-endpoint-create.md) on Server B. Enable cloud tiering. Temporarily set the volume free space policy to 99% so that you can tier as many files as possible to the cloud. ## Step 2: Copy data to the temporary VM Use Robocopy, a file copy tool built into Windows, to copy the data from Server A to Server B. Run the following command from the Windows command line on Server A: ```console robocopy <Server A SourcePath> <Server B Dest.Path> /MT:16 /R:2 /W:1 /COPYALL /MIR /DCOPY:DAT /XA:O /B /IT /UNILOG:RobocopyLog.txt ``` ## Step 3: Transition users to the temporary VM Removing user access to your server endpoints causes downtime. To minimize downtime, perform these steps as quickly as possible: 1. Remove SMB access to the server endpoints on Server A. Don't delete the server endpoints yet. 1. On Server A, change the startup type of the Storage Sync Agent Service from **Automatic** to **Disabled**, and then put it in the **Stopped** state. This change prevents the sync agent from uploading changes while you run the final Robocopy. 1. Run Robocopy again to copy any changes that happened since the last run. From Server A, run: ```console robocopy <SourcePath> <Dest.Path> /MT:16 /R:2 /W:1 /COPYALL /MIR /DCOPY:DAT /XA:O /B /IT /UNILOG:RobocopyLog.txt ``` 1. Enable SMB access to the server endpoints on Server B. Users can now access the file share from the temporary VM (Server B). 1. On Server A, change the startup type of the Storage Sync Agent Service from **Disabled** to **Automatic**, and then put it in the **Started** state. ## Step 4: Delete old server endpoints and replace the drive > [!IMPORTANT] > Before proceeding, verify that the Storage Sync Agent Service on Server A is in the **Started** state (as configured in Step 3, sub-step 5). The agent must be running to delete server endpoints. If the agent is disabled, server endpoint deletion fails. When you're sure that user access is restored, [delete the server endpoints](file-sync-server-endpoint-delete.md) on Server A. Replace the drive on Server A. Make sure the drive letter of the replaced drive is the same as it was before the replacement. ## Step 5: Create new server endpoints and copy data to the new drive Re-create the server endpoints on Server A. Enable cloud tiering. Temporarily set the volume free space policy to 99% so that you can tier as many files as possible to the cloud. Use Robocopy to copy the data to the new drive on Server A. Run the following command from the Windows command line on Server B: ```console robocopy <Server B SourcePath> <Server A Dest.Path> /MT:16 /R:2 /W:1 /COPYALL /MIR /DCOPY:DAT /XA:O /B /IT /UNILOG:RobocopyLog.txt ``` ## Step 6: Restore user access to the registered server Removing user access to your server endpoints on the temporary VM causes downtime. To minimize downtime, perform these steps as quickly as possible: 1. Remove SMB access to the server endpoints on Server B. Don't delete the server endpoints yet. 1. Run Robocopy again to copy any changes that happened since the last run. From Server B, run: ```console robocopy <SourcePath> <Dest.Path> /MT:16 /R:2 /W:1 /COPYALL /MIR /DCOPY:DAT /XA:O /B /IT /UNILOG:RobocopyLog.txt ``` 1. Ensure that the Storage Sync Agent Service on Server A is in the **Started** state. 1. Enable SMB access to the server endpoints on Server A. 1. Sign in to the Azure portal. Go to the sync group and verify that the cloud endpoint is syncing to the server endpoints on Server A. Users should now be able to access the file share from your registered server. 1. Change your volume free space policy to a reasonable level, such as 10-20%. ## Step 7: Clean up the temporary VM After you confirm that Server A is operating normally, complete these steps: 1. [Delete the server endpoints](file-sync-server-endpoint-delete.md) on Server B. 1. [Unregister Server B](file-sync-server-registration.md#unregister-the-server) from the Storage Sync Service. 1. Decommission the temporary VM (Server B).