Overview

This article described the procedure to manually test the VSS Shadow Copy Creation Using the Diskshadow Utility in Windows on when a Shadow Copy creation fails during Druva Backups.
During a Microsoft SQL Backup, Druva instructs Microsoft Volume Shadow Copy Services (VSS) to create a shadow copy of the server.
Druva uses these shadow copies to create a backup of your server data. The Shadow Copy creation can result in a failure during SQL Backups.
This article will help to test the Shadow Copy creation manually and outside of Druva to isolate the issue.

A. PREREQUISITES

The VSS Writers on the Servers, especially the SQL VSS Writer in case of a SQL Backup, must be Stable and not present any Errors.
To verify that, you can run the following command on your Server: vssadmin list writers
In case the SQL VSS Writer appears with an Error, does not appear as 'Stable' or does not get listed at all, then we recommend rebooting the SQL Server to restart the VSS components.
Most of the time this will help all VSS Writers on your Server to be reset and show as stable with no errors.
After rebooting please run the same command 'vssadmin list writers' again to ensure the VSS Writers are Stable with No Error.

Open the Command Prompt or Powershell Window as Administrator on your Server
Launch Diskshadow with logging enabled running the command below:
- diskshadow
Enable verbose mode
- set verbose on
Set context to volatile so that the Shadow copy is deleted when Diskshadow is closed.
- set context volatile
Find the volume we are trying to create the Shadow Copy for, running the command mountvol on your Server.
- mountvol
Add the volume we are trying to create the Shadow Copy for, with its UUID:
- add volume \\?\Volume{xx-xxxx-xxxx-xxxx}\
Find the WriterID of the VSS SQL Writer.
- Run the command below on the SQL Server. The Writers will all appear, with their IDs.
  - vssadmin list writers
- Note: The Writers ID looks like this: a65faa63-5ea8-4ebc-9dbd-a0c4db26912a.
Verify the VSS SQL Writer running the following command:
- writer verify {WriterID}
- Example: writer verify {a65faa63-5ea8-4ebc-9dbd-a0c4db26912a}
Enter the following command:
- begin backup
Initiate Shadow Copy creation and observe the outcome.
- create
  - Note:
  - Wait, verify results and send us an email to let us know the result.
  - In case of success:
  - Please copy and save the Shadow Copy ID created
End the Backup running the command below:
- end backup
Delete Shadow copies
- delete shadows {shadow copy ID of the created shadow}
- Note: The {shadow copy ID of the created shadow} is from the Step # 10 that you copied earlier.

In case Step #10 fails it means that the Shadow Copy creation is failing in Windows.
It means that the VSS Writer specified on step #7 is not able to create a Shadow Copy of the Volume selected on Step # 6.
When this fails, there is usually an Error reported in the Application Event logs on your Server.
We recommend reviewing the Error in the Event Logs and investigate this issue further in Windows.