DC errors during backup Veeam7 and Server 2012

[davidb1234]

We see this error on both our physical and virtual DC during a veeam backup of the virtual DC. Why does backing up a virtual DC causing a problem with accessing SYSVOL?????

I am aware of the issue with backing up multiple DCs at the same time however that is not the case here. We only have a single virtual DC and we don't back up the physical DC yet somehow during backup it causes SYSVOL access issue.

DC1
* Event Time: 25 Oct 2013 02:18:28 PM
* Source: Microsoft-Windows-GroupPolicy
* Event Log: System
* Type: Error
* Event ID: 1058
* Event User: NT AUTHORITY\SYSTEM
* The processing of Group Policy failed. Windows attempted to read the file \\web.local\sysvol\web.local\Policies\{A1572D80-8CA1-49C9-89B4-E0494B01D910}\gpt.ini from a domain controller and was not successful. Group Policy settings may not be applied until this event is resolved. This issue may be transient and could be caused by one or more of the following:
a) Name Resolution/Network Connectivity to the current domain controller.
b) File Replication Service Latency (a file created on another domain controller has not replicated to the current domain controller).
c) The Distributed File System (DFS) client has been disabled.

DC2
* Event Time: 25 Oct 2013 02:17:11 PM
* Source: Microsoft-Windows-GroupPolicy
* Event Log: System
* Type: Error
* Event ID: 1058
* Event User: NT AUTHORITY\SYSTEM
* The processing of Group Policy failed. Windows attempted to read the file \\web.local\sysvol\web.local\Policies\{A1572D80-8CA1-49C9-89B4-E0494B01D910}\gpt.ini from a domain controller and was not successful. Group Policy settings may not be applied until this event is resolved. This issue may be transient and could be caused by one or more of the following:
a) Name Resolution/Network Connectivity to the current domain controller.
b) File Replication Service Latency (a file created on another domain controller has not replicated to the current domain controller).
c) The Distributed File System (DFS) client has been disabled.

[Gostev]

I/O halt during VSS freeze?

[foggy]

David, it is actually expected that SYSVOL and NETLOGON shares are temporarily not available during the backup process. Seems that at this very moment domain controller attempted to update group policy and failed due to share unavailability. If this is the only message you're observing, then everything is back operating again as it should. Do you see any other error messages after the backup is complete?