Agent-based backups for Windows and Linux, centralized agent management
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Joined: Jan 12, 2018 11:20 pm
Full Name: Control
Location: Washington, USA

Backup Takes Very Long Time with Long VSS Snapshot

Post by controlfreak »

I was experiencing an issue with intermittent, extremely long VSS snapshot creation times. When I run a job to backup shares on a DFS file server, the VSS snapshot either takes 4 minutes or 24 hours 4 minutes to create the snapshot. The job will eventually succeed, but this 24 hour backup job wreaks havoc on my backup server's DFS replication and on the associated veeam repository on the file server.

Support helped me check the VSS Writer list. All were in a good state. We also ran a VSS trace, which was inconclusive.

While testing pausing DFS replication during the backup, I discovered the following Error 513 in the Application Event Log:

An error occurred in Cryptographic Services while processing the OnIdentity()call in System Writer Object.

AddLegacyDriverFiles: Unable to back up image of binary Microsoft Link-Layer Discovery Protocol.

System Error:
Access is denied.

The cause of this error is related to the VSS writer not having permissions to the NT AUTHORITY\SERVICE.

The fix:
  • Open an administrative Command Prompt window, and then run the following command to check the current permissions:
  • sc sdshow mslldp
  • Copy the output string from step 1, append it with (A;;CCLCSWLOCRRC;;;SU), and then run the following command to add the access permission to Mslldp.dll:
  • sc sdset mslldp <string>
  • For example, run the following command:
See ... ows-server for details.

The above steps resolved my issues with 24 hour VSS snapshot creation times.

Hope this helps someone else.

Ticket# 03911669



Veeam Software
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Re: Backup Takes Very Long Time with Long VSS Snapshot

Post by HannesK »

thanks for supporting the community by posting a solution đź‘Ť

Best regards,

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