Microsoft Failover Clusters are fully supported by Veeam Agent for Microsoft Windows when managed by Veeam Backup & Replication.
Veeam Agent for Microsoft Windows operating in the standalone mode does not support Microsoft Failover Clusters. The behaviors you can expect when Veeam Agent for Microsoft Windows operates in standalone mode on a cluster node are described below. Veeam Agent for Microsoft Windows operating in standalone mode, not managed by Veeam Backup & Replication, is not cluster aware, as such failover may cause unexpected and unsupported results. Cluster features are not supported.
The current article covers cluster backup workarounds which could be used for a standalone version of Veeam Agent for Microsoft Windows.
Keep in mind that Windows Server Failover Cluster is completely supported in Agent Management functionality. The following article contains all the details on how to set it up - https://www.veeam.com/kb2463
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