To protect the DFS or DFSR Cluster data, Backup Exec must use the DFSR writer to protect the data correctly.  

On the cluster nodes owning the "File Server" DFS or DFSR resource, select the Shadow Copy Components - User Data - Distributed File System Replication selections. (Figure 1).

Figure 1

NOTES:
- Do not select the DFS or DFSR drive letters under the "File Server" or DFS /DFSR Cluster Name.  If the drive are selected under Cluster Name, the data is automatically excluded from backup due to Active File Exclusion on the DFS / DFSR folders.
- Due to the remote agent process caching caching VSS writer information, after cluster failover the Backup Exec Remote Agent for Windows service (BEREMOTE.EXE) will need restarting on the new active node (unless the backup job does not need to run immediately).  The agent will eventually refresh the VSS writer information as a background process. A restart of the service forces this to happen immediately.