Consider the following scenario:
- You're using a Windows Server 2012, Windows Server 2012 R2, or Windows Server 2016 cluster.
- You changed the Properties for the Cluster Network Name Resource so that the DNSName and Name Property are different than the Name of the Cluster Network Name Resource. For example, you run the following PowerShell cmdlet:
Get-ClusterResource "ClusterNetworkNameResource" | Get-ClusterParameter
Object Name Value Type------ ---- ----- ----ClusterNetworkNameResource Name ServerNameX StringClusterNetworkNameResource DnsName ServerNameX String
- You create a file share in this cluster group with the CA Feature enabled.
Log Name: WitnessClientAdminSource: Microsoft-Windows-SMBWitnessClientEvent ID: 8Level: ErrorDescription:Witness Client failed to register with Witness Server for notification on NetName with error (The parameter is incorrect.)Note This event could also be logged with for a file share without the CA Feature enabled.
The Purpose of the SMB Witness Service is to speed up the Detection of Cluster Node Failures. This SMB Witness Service is only active for clustered CA Shares. For Non-CA Shares the SMB Witness Service is not used.
If the Event ID 8 is logged and the Witness Client could not register for a Cluster Network Name / CA File Share then this is equal to if the SMB Witness Service is disabled.
A Cluster Node Failure is first found during the Cluster Service Health Checks and the SMB Witness Service also gets this Information immediately from the Cluster.
Next the SMB Clients are notified from the SMB Witness Service that they need to re-connect to the remaining Cluster Nodes. This Process is finished in a few Seconds. If the SMB Witness Service is not running then the SMB Client needs to rely on the TCP and SMB Timeouts. Depending on the Configuration this can take about 45-90 Seconds till the Client notices the Cluster Node Outage and re-connects to the remaining Cluster Nodes. In some special Configurations it can take multiple Minutes till the Cluster Node Outage is notified.
The SMB Witness Service is not necessarily needed to enable CA but it is recommended to have this Service running in Default Configurations as this speeds up the Detection of Node Failures. Nevertheless the CA Feature is fully supported with disabled SMB Witness Service.