→ Applies to: Hyperion 9.x and above

Symptom

During the execution of VM protection tasks, Windows virtual machines may show one or more of the following behaviors:

• Backup fails or stalls during the file system freeze/thaw phase;
• Windows services (e.g. MSSQL, Exchange) report errors or temporary interruptions;
• After backup, the VM appears slow or unstable;
• Backups are inconsistent or unusable during restore.

You may also receive errors such as "Invalid backup chain detected for database" or "Error 3041: Failed to create backup for database" when trying to perform an incremental or differential backup.

These symptoms suggest a problem with guest file system lock management during backup operations involving the QEMU Guest Agent.

Solution

Step 1. Login to SynetoOS GUI

Step 2. Select the VM you want to access via the Console, then click on the console window (the black screen on the right, under the “Screen” label).

Step 3. Run the command “regedit” to open Registy Editor

Step 4. Navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\QEMU Guest Agent VSS Provider

Step 5. Right click on VssOption, then select Modify

If VSSOption is not listed, it must be created by following Step 8 (Optional) and Step 9 (Optional)

Step 6 (Optional). Right-click VssOption, select New, and then choose DWORD (32-bit) Value

Step 7 (Optional).  Rename the new DWORD (32-bit) Value to VssOption

Step 8. Right click on VssOption, then select Modify

Step 9. Change Value data to 5, then click OK

Step 10. Reboot Windows VM