VMs that are clustered together with Microsoft Clustering Services will not backup in vRanger.
Microsoft Clustering Services (not to be confused with VMWare clustering/clusters) need to use storage that is shared simultaneously between nodes of the Microsoft Cluster. This shared storage contains the Microsoft quorum resource (which is the "traffic cop" of the cluster, keeping track of which node "owns" which clustered resources), as well as any shared file storage/application storage defined by the cluster. This is done so that during a failover operation, the cluster node which fails can "give" its resources to the surviving cluster node(s), as they are shared in common between them. However, this requires the VMs to be setup in VMware with a paravirtualized SCSI adapter in Bus-sharing mode. VMs which use bus-sharing cannot have a snapshot taken of them, so the backup attempt of these machines fails at the snapshot phase at the beginning of the backup.
Bus-sharing VMs cannot be backed-up with vRanger using the standard VM backup method; alternate backup methods must be used (i.e. agent-based backup software, etc.) VMs using the paravirtualized SCSI adapter may be backed up, provided they are NOT using bus-sharing as part of the paravirtualized SCSI adapter setup.
In order to backup VMs that have been clustered using Microsoft Clustering Services you can use the vRanger Physical Backup process by deploying the vRanger Physical Client agent on the servers, then performing a physical backup using vRanger.
For more information regarding physical backups, please see the vRanger User's Guide